The script is setup to take in, as its first parameter, the name of the
example to build. This is then checked against the valid examples and
matched with the associated directory. The directory is then checked for
in the current path - if not, it's an indication that the script was not
sourced from the project root.

The script now sets up the virtual environment directory and installs
the required python dependencies from requirements.txt.

Note: This script may have compatibility issues with Windows that will
be addressed in a separate issue.

This commit saw a few major changes, including a correction to the
target board variable. The mount point is now passed in as an argument
to the script as there's an issue with flashing with mbed-tools; please
refer to issue #282 on the mbed-tools repository for more information.
As a result, the binary is flashed manually.

The script has many caveats that are addressed as a comment on the
associated issue (or pull request). These are mainly as a result of
dependency conflicts between mbed-tools, mbed-os, and pyocd. The updated
script follows the build instructions as listed in the documentation
accompanying this example (with additional checks).

This commit is the first in a series of refactoring commits. It
introduces a new tool, fota.sh. This commit sets up the script with an
author's note and a function to display the tool's usage.

The options passed into the script are parsed and stored in the
corresponding variables. Note that some of these variables have default
values (as indicated by the usage message).

This commit also removes the print_options function, which was created
to help debug the functionality of the parse_options function.

The file is setup with constants for text formatting.

The say function prints a message to the console with formatting based
on the selected formatting mode. For now, the error message
functionality of this function has been implemented. Refer to the
comments in the script for more information.

The function prints an error message to stderr and exits or returns with
a code of 1 based on the fail mode, which is passed as an input. If the
file is being sourced, then "return" would be passed in; else "exit"
would be passed in. This function invokes the say function created
earlier with the error formatting mode.

Previously, the parse_options function required that the option be
followed by an '=' symbol and the value (i.e -o=value or
--option=value). The usage instructions separate the option and the
value by a space and the function was modified to meet this requirement.

The following stack overflow post proved quite useful in understanding
how options are parsed - in fact, the "Bash Equals-Separated" part of
the accepted answer was adapted for the intial implementation.

https://stackoverflow.com/a/14203146

The parsing function would loop indefinintely if there was no value
associated with an option. There is still a need to check if the default
value of the options have been cleared, in which case the prior default
must be restored or an error must be displayed indicating that the
option was not followed by a value.

This commit rolls back the parsing function to it's state in commit
a58f3b9. The equals-separated parsing
seems a bit more robust than space-separated parsing. I did experiment
with getopt, which didn't work as the version pre-installed on macOS
doesn't support long option parsing. The 'enhanced' getopt would require
a separate installation - at this phase, a python script seems easier.

The fota script now sources the utils script and uses the fail and
setup_formatting functions to handle the error of unrecognised options
in the parsing phase.

A note is displayed if no mount point is specfied indicating that the
binaries will have to be flashed manually.

The message is now updated to use the note formatting and the second
line was dropped as it was redundant.

The build instructions were adapted from those defined earlier in
build.sh. This function has been verfied to work with the supported
target board and supports building without a mount point.

Create mock_clean and mcuboot_clean; the latter is still a dummy
function. The former has been implemented and verified to clean the
target build directory and dependencies directories.

The build instructions for the requirements installation were adapted
from those defined earlier in build.sh, albeit with minor changes.

These instructions go upto the point where the original virtual
environment is restored. The last step would involve some input from the
user to modify the mbed_app.json file in the application folder.

This is quite a significant commit - the script now prompts the user on
whether it should auto-update the application/mbed_app.json file; this
serves well for testing purposes where the "yes" would be piped into the
script. Also, part of the script was adapted from the prior
implementation in build.sh.

Note that this introduces a new dependency "jq" that's not installed
through pip - rather, it requires some manual intervention on the
end-user's behalf.

These steps were adapted from the ones written earlier in build.sh.

The trap invokes clean upon unsuccessful termination.

If there are a number of build files to clean, there is quite a
significant pause from when an error occurs to when control is handed
over to the user. This message indicates to the end-user what's going on
during that time.

Please refer to the comments in the .yml file for more information

Build process automation

…fota into ci-setup

CI Setup

Revert "CI Setup"

…fota into ci-setup

Fix dependency issue in workflow

The workflow is no longer triggered on a push to main. This was done to avoid duplicate runs when a pull request is merged.