Allow modifying ignored files for build

[darcien]

Right now bob has hardcoded ignore pattern when building:

react-native-builder-bob/packages/react-native-builder-bob/src/utils/compile.ts

Line 34 in 6650bc1

ignore: '**/{__tests__,__fixtures__,__mocks__}/**',

Not all projects follow this pattern.
I would like to be able to modify this ignore pattern without patching the sources.

This has been raised multiple times with no clear responses or solutions:

• Allow configuring ignore/exclude files settings #197
• How can i exclude **.test.ts files & include __mock__ folders in the commonjs target? #162
• Support custom source file ignore #325

[atlj]

We can leverage the bob config to make it possible to customize it. Will see what can be done.

[atlj]

Please see #450

[darcien]

That PR looks perfect, thank you!

[atlj]

Closing this as #450 is merged.