CB-12835: add a Context getter in CordovaInterface

[dreifachstein]

A custom engine may live outside of the Activity's lifecycle and the
Activity instance may not always be available. This getter allows
Context accesses in all cases.

[codecov-io]

Codecov Report

Merging #385 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #385   +/-   ##
=======================================
  Coverage   39.52%   39.52%           
=======================================
  Files          16       16           
  Lines        1551     1551           
  Branches      277      277           
=======================================
  Hits          613      613           
  Misses        938      938

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3a6e898...1790673. Read the comment docs.

[filmaj]

Does anything need to change in the plugin authoring documentation for Android as a result of this?

https://cordova.apache.org/docs/en/latest/guide/platforms/android/plugin.html

Maybe the Android Integration section needs updating? It references that the context is no longer available?

[infil00p]

@filmaj Yeah, that definitely needs an update.

[filmaj]

OK, I'm cool with these changes but we absolutely need to update the docs in a separate PR as well.

[infil00p]

Did anyone ever get around to writing that doc update? Anyone have the link to the PR?

[infil00p]

Yeah, this isn't that big of a deal to document, I'm going to merge this in now.