Regex overrides improvements

[aurimasmi]

Is your feature request related to a problem? Please describe.
Currently regex overrides doesn't take into account if override was already applied. Therefore we need to write complex and weird patterns just to avoid override being applied every time platform being run.

Example of @flexn/create override

In this override I want to add new import which comes right away after last import. But I can't simply do something like:

"import Platform from '../../Utilities/Platform';": "\nimport NativeModules from '../../BatchedBridge/NativeModules';"

because if I do that next time I run my app, rnv recognizes that my pattern is still exists(because I appended string not override) and it will apply my override again and again.

And this is one of examples even in the same file rest of overrides also facing same issues that's why there are complex patterns.

Describe the solution you'd like
My expectations is that whatever pattern is added there rnv should recognise that it was already executed and ONLY execute it again if something changed in that pattern