consolidate Linux install scripts

[qrkourier]

Presently,

• install.bash - adds RPM or DEB repo source for non-ZET packages
• install-ubuntu.bash - adds DEB repo source for ZET on Ubuntu
• Non-Ubuntu Debian and all RedHat distros must configure ZET repo sources manually
• GnuPG must be pre-installed on Debian distros for managing the package signing pubkey

1. Enhance install.bash to:

   • handle ZET and non-ZET package repos for Debian and RedHat distros
   • install GnuPG, if missing, on Debian distros

2. Update ziti-doc to utilize the enhanced install.bash

3. Deprecate install-ubuntu.bash - set decommission date, e.g., in 180 days

[qrkourier]

@scareything pointed out that we should separate the repo setup from the package install step. Here's two ideas we can accomplish that.

setting up repos with a script

Presently, we have install scripts that detect the distro, configure a repo, and install a package.

Instead of consolidating install-ubuntu.bash and install.bash, we could deprecate them both with a new script like openziti-setup.bash that is inclusive of ZET (distro-version-specific) and non-ZET (distro-family-specific) packages, and only detects the distro and distro version, and configures both ZET and non-ZET repos.

Then, the Linux admin must install whichever package they need: openziti, ziti-edge-tunnel, etc.

The new openziti-setup.bash script would, like the existing install scripts, manage the Linux package repo metadata signing pubkey.

set up repos with a package

While the openziti-setup.bash idea could manage any change to the repo setup, the Linux admin must notice a problem or see an announcement to know when to re-download and re-run the script to adopt such changes, like a new signing key or new repository source.

We can eliminate those admin steps by shipping these changes as an openziti-setup package (related issue about this in the ZET repo).

The Linux admin download/install experience would change like this:

1. Add the current distro-family repo: RedHat or Debian.
2. Install openziti-setup. The package configures the system with any appropriate repos (e.g., the distro-version repo for ZET), refreshes the signing pubkey as needed, etc.
3. Install any package available from OpenZiti now or anytime in the future without any further manual setup.

This assumes the admin accepts future upgrades of the openziti-setup package. If they don't for some reason, the fix is to upgrade that package then install whatever didn't work the first time.