[RN][Testing] Update testing scripts to work with any version of React native

[cipolleschi]

Summary:

These changes updates the testing script so that it follow the approach described here.

In this way, the testing script:

• Is not bound to a single version of React Native
• Does not require that we publish an rc.X version of the template before we release rc.X of React Native

Changelog:

[Internal] - Update testing script to work with any version of React Native

Test Plan:

Tested locally and verified that the script is packing a template and using the template when initializing the project.

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
android	hermes	arm64-v8a	20,443,812	+142,913
android	hermes	armeabi-v7a	n/a	--
android	hermes	x86	n/a	--
android	hermes	x86_64	n/a	--
android	jsc	arm64-v8a	23,642,505	+145,011
android	jsc	armeabi-v7a	n/a	--
android	jsc	x86	n/a	--
android	jsc	x86_64	n/a	--

Base commit: 8db2995934b7ed313d16de8fbc005eece504a91f Branch: main

[cortinico]

I tested this locally on the 0.75-branch and I was able to successfully e2e test the template 🎉