feat: support custom compileSdk setting

[erisu]

Motivation and Context

closes #1310
closes #1373

Allow setting a custom compileSdkversion, different from targetSdk.

Some libraries might require a higher compileSdk while it can still target a lower Sdk.

Generally it is recommended that the targetSdk and compileSdk match.

If a user decides to increase the targetSdk, they will now need to also manually bump the compileSdk or it will remain behind.

Description

Can set custom compileSdk version with the follow preference:

<preference name="android-compileSdkVersion" value="31" />

A warning will display during the platform add and prepare step when the targetSdk is higher then the compileSdk.

Even if the build passes, there could be potential errors further down.

Testing

npm t

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[codecov-commenter]

Codecov Report

Merging #1431 (30fbc85) into master (e730000) will increase coverage by 0.02%.
The diff coverage is 76.19%.

@@            Coverage Diff             @@
##           master    #1431      +/-   ##
==========================================
+ Coverage   73.20%   73.22%   +0.02%     
==========================================
  Files          21       21              
  Lines        1646     1666      +20     
==========================================
+ Hits         1205     1220      +15     
- Misses        441      446       +5     

Impacted Files	Coverage Δ
lib/prepare.js	44.47% <0.00%> (-0.14%)	⬇️
lib/check_reqs.js	71.05% <76.47%> (+0.68%)	⬆️
lib/create.js	94.32% <100.00%> (+0.08%)	⬆️

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[erisu]

Downside of allowing custom compileSdk..

• Plugins can take control of defining the version and users may not notice it changed.. Might lead to issues
• If multiple plugins define the version, the compileSdk version from the last installed plugin is used. If the version is lower then another plugins defined version, errors might appear.
  • Usually it is recommended that the app developer sets the value in the config.xml and not controlled by plugin developers in plugin.xml. Plugin developers should only document the requirement.
• Some plugins may not be well maintained and if they defined the compileSdk it would lock the app from upgrades.
• If the user bumps the targetSdk, the compileSdk will no longer be in sync. The users will now have to manually control the compileSdk.

[breautek]

If the user bumps the targetSdk, the compileSdk will no longer be in sync. The users will now have to manually control the compileSdk.

This might be difficult since we use a JSON file to set our defaults... but wonder if there's a way to default compileSdk to the value of targetSdk.

[breautek]

I've made a collection of suggestions that if accepted... probably should be applied together.

The attempt is rather than explicitly declaring the COMPILE_SDK_VERSION default to a hard-coded value, is to make it's default the same as SDK_VERSION.

The suggested changes I believe will work (but untested) so that unless explicitly declared, compile SDK will be whatever what target SDK is set to (even if the user changes the target SDK).

e.g.:

Use Case 1

User does not declare either target or compile

Target defaults to 32, as defined in defaults json.
compile will default to target, which is set to 32.

Use Case 2

User explicitly sets target sdk to 33

Target will be set to 33 from config preferences.
Compile will default to target, which is set to 33.

Use Case 3

User explicitly sets compile sdk to 33

Target sdk will be set to 32, which comes from the defaults json.
Compile sdk will be set to 33, which comes from config preferences.

Use Case 4

User explicitly sets both target to 30 & compile sdk to 32

Target sdk will be set to 30, which comes from config preferences.
compile sdk will be set to 32, which comes from the config preferences.

Let me know of your thoughts, or whether if this is even a good or bad idea.

[dpogue]

LGTM

[erisu]

Thank you for the review & votes!