Optimize code and string allocations

[rubensousa]

• Used StringBuilder to construct json strings instead of keeping N copies of the entire string in memory. This makes JsonObjectWrapper and PayloadObject a lot faster and use less memory
• Load JS code from assets instead of using static strings in memory

Benchmark test on my Pixel 6:

JsonObjectWrapper.collectionToJsonString, 1000 elements:

Before: 2964 ms, After: 106 ms

JsonObjectWrapper.mapToJsonString, 1000 properties:

Before: 1014 ms, After: 55 ms

[TheRishka]

@bwalter @wkarl we would need some support here :)

[bwalter089]

The re-format (which makes sense) and the move to truth (I am not sure about the benefit here ;)) make it a little bit hard to review the real changes but the optimizations are very welcome additions, thanks a lot for your work! Looks good to me,

[bwalter]

Thanks for the good change!

[rubensousa]

The re-format (which makes sense) and the move to truth (I am not sure about the benefit here ;)) make it a little bit hard to review the real changes but the optimizations are very welcome additions, thanks a lot for your work! Looks good to me,

I added Truth because the expected and actual were reversed from the junit assertions, which made it harder for me to analyse why the tests were not green in the beginning

[bwalter]

The re-format (which makes sense) and the move to truth (I am not sure about the benefit here ;)) make it a little bit hard to review the real changes but the optimizations are very welcome additions, thanks a lot for your work! Looks good to me,

I added Truth because the expected and actual were reversed from the junit assertions, which made it harder for me to analyse why the tests were not green in the beginning

Fair point. Rust std lib uses left/right instead of expected/actual to avoid the issues ;)