[PLAT-5950] Store source maps in $TMPDIR during Xcode build phases

[nickdowell]

Goal

Fix building projects whose build directory path contains whitespace.

The underlying issue is that react native's script cannot accept any paths containing spaces in $EXTRA_PACKAGER_ARGS

Design

A new location has been designated for the source map: $TMPDIR/$UID-main.jsbundle.map

This path is guaranteed to not contain any whitespace, which will fix compatibility with react-native-xcode.sh

Use md5 to generate a unique $UID from the build path; unique for that project, build configuration and target.

The script will fall back to the previous location to remain compatible with the old source map location, for Xcode projects that have not been updated.

Testing

Manually tested using sample RN projects.

Tested by following instructions from #1140 against a freshly created react native app.

[github-actions]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	40.76 kB	12.57 kB
After	40.76 kB	12.57 kB
±	No change	No change

code coverage diff

Coverage values did not change👌.

Total:

Lines	Branches	Functions	Statements
0%(+0%)	0%(+0%)	0%(+0%)	0%(+0%)

Generated by 🚫 dangerJS against ae17565

[bengourley]

Looks good. I tested with a project set up with the old version of the cli, using the new version of the notifier and it falls back nicely.

Just needs a changelog entry.