fix: ANDROID_SDK_ROOT variable

[breautek]

Platforms affected

Android

Motivation and Context

Fixes #949 which describes a functional issue
Fixes #670 which describes a cosmetic issue that is loosely related.

Description

This PR depends on two other PRs: #959 #960

This PR does the following:

• Makes ANDROID_SDK_ROOT the primary variable to look for the Android SDK location.
• Makes ANDROID_HOME the fallback variable, if ANDROID_SDK_ROOT is not present/valid.

Gradle updates:
Note that the following gradle updates were required, otherwise the android gradle plugin did not honour the ANDROID_SDK_ROOT variable.

• Updates the framework's android studio's gradle plugin from version 3.3.0 to 3.5.3.
  Not only this is required for android's gradle to obey ANDROID_SDK_ROOT, it is now in sync with the Android test project/
• Updates the Androidx test project to use gralde plugin from version 3.3.0 to 3.5.3, to match Android Test & framework.
  • Consequentially, this required to also upgrade AndroidX test project to use Gradle 6.1, which also matches both the Android test project & framework

Gradle updates have been moved to independent PRs #959 #960

These changes above fixes #949

Additionally, since we update the environment variables dynamically, the environment variable printout produced misleading information.
The environment variable printout will now print out the variable as defined by the user (before the tooling messes with them). An additional log
is printed that tells the user exactly what Cordova is going to use for the Android SDK path. This should fix #670

Tests was also changed to mainly use ANDROID_SDK_ROOT instead of ANDROID_HOME. Additional tests were added to ensure things works with either variable, but ANDROID_SDK_ROOT now takes precedence over ANDROID_HOME, should both be defined.

Testing

npm test passes successfully, both old and new.
I've ran npm test in every combination of:

• with ANDROID_SDK_ROOT / with ANDROID_HOME
• with ANDROID_SDK_ROOT / without ANDROID_HOME
• without ANDROID_SDK_ROOT / with ANDROID_HOME
• without ANDROID_SDK_ROOT / without ANDROID_HOME

Additionally, I've tested each of these combinations with a hello world cordova test app, to ensure build runs successfully.

This PR should be accompanied with a cordova-docs PR to update the Environment Variables documentation, which has not been done yet.

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

[breautek]

Not sure why it's failling on mac, NodeJS on mac must behaves slightly different, will investigate tomorrow.

Also pondering forcing ANDROID_HOME from the environment after a correct sdk path is determined considering...

If ANDROID_HOME is defined and contains a valid SDK installation, its value is used instead of the value in ANDROID_SDK_ROOT.

https://developer.android.com/studio/command-line/variables#android_sdk_root

[codecov-io]

Codecov Report

Merging #951 into master will increase coverage by 0.56%.
The diff coverage is 86.84%.

@@            Coverage Diff             @@
##           master     #951      +/-   ##
==========================================
+ Coverage   65.53%   66.10%   +0.56%     
==========================================
  Files          21       21              
  Lines        1828     1838      +10     
==========================================
+ Hits         1198     1215      +17     
+ Misses        630      623       -7     

Impacted Files	Coverage Δ
bin/templates/cordova/lib/check_reqs.js	57.60% <86.84%> (+5.42%)	⬆️

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[erisu]

• Rebase PR
  • Re-run the lint after rebasing. I believe there are some cases that will be caught with the new lint version.
• Revert all gradle changes and move those changes into its own PR

[breautek]

Putting this PR back to "WIP" since the latest rebase, this branch specifically does not pass a test for some reason... the test that is failing seems unrelated, so will need to investigate...

Oddly enough, it doesn't fail in the other 2 branches that this PR depends on, so it is something specific to this branch.