[monorepo] Fix flytectl install script

[eapolinario]

Why are the changes needed?

The script used to install flytectl needs to be updated to reflect the move to the monorepo.

What changes were proposed in this pull request?

The install.sh script used to be generated by godownloader, but that tool has been deprecated for at least 2 years. I couldn't get it to work with relatively recent versions of go (I went as far as 1.18). Another problem is that the tool is not aware of the pattern we've been using to release flytectl from the monorepo (specifically the fact that releases have git tags containing the flytectl/ prefix).

Taking all that into consideration, there are two changes worth reviewing in this PR:

1. We now require jq to be able to parse the valid versions of flytectl
2. We use the official github api to list all releases, since the old endpoint used didn't return the flytectl releases (due to the fact that the tags associated with those releases have the flytectl/ prefix, e.g. https://github.com/flyteorg/flyte/releases/tag/flytectl%2Fv0.8.21).

Once this is merged we'll be able to modify the scarf entry that points to the install script to point to https://raw.githubusercontent.com/flyteorg/flyte/master/flytectl/install.sh.

How was this patch tested?

I tested locally in both linux and mac. I made sure to exercise the code paths for both when a version is specified and not specified.

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

Docs link

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.10%. Comparing base (2143948) to head (163b65b).
Report is 131 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5405   +/-   ##
=======================================
  Coverage   61.09%   61.10%           
=======================================
  Files         793      793           
  Lines       51156    51156           
=======================================
+ Hits        31256    31257    +1     
+ Misses      17028    17027    -1     
  Partials     2872     2872           

Flag	Coverage Δ
unittests-datacatalog	69.31% <ø> (ø)
unittests-flyteadmin	58.90% <ø> (ø)
unittests-flytecopilot	17.79% <ø> (ø)
unittests-flytectl	68.31% <ø> (ø)
unittests-flyteidl	79.30% <ø> (ø)
unittests-flyteplugins	61.94% <ø> (ø)
unittests-flytepropeller	57.32% <ø> (ø)
unittests-flytestdlib	65.75% <ø> (+0.02%)	⬆️

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