feat(cli): support shorthand aliases for languages

[ren-yamanashi]

Fixes #748

Description Changes

Extended the --language option values for the cdk init and cdk migrate commands to support shorthand aliases for language like ts and js.

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[iankhou]

Nice improvement for usability. Can we add a negative test case for invalid languages/aliases for init and migrate?

[ren-yamanashi]

@iankhou

Thank you for the approval!

The build was failing, so I've made the necessary minor fixes.
Could you please approve (and run CI build) again?

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commits:

da364b1

6f884a6

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.83%. Comparing base (5fc1b13) to head (6f884a6).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #814      +/-   ##
==========================================
+ Coverage   82.60%   82.83%   +0.22%     
==========================================
  Files          64       65       +1     
  Lines        9465     9509      +44     
  Branches     1106     1120      +14     
==========================================
+ Hits         7819     7877      +58     
+ Misses       1612     1598      -14     
  Partials       34       34              

Flag	Coverage Δ
suite.unit	82.83% <100.00%> (+0.22%)	⬆️

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