fix: workaround for npm ignoring .gitignore

[tido64]

Description

npm install seems to be renaming .gitignore files to .npmignore. This breaks our templates. As a workaround, we'll rename the files ourselves, from .gitignore to _gitignore, to avoid any further attempts to mutate the package.

Resolves #1228.

Platforms affected

• Android
• iOS
• macOS
• Windows

Test plan

npm pack
tar tf react-native-test-app-0.0.1-dev.tgz | grep gitignore

Verify that .gitignore files have been renamed to _gitignore, i.e.:

% tar tf react-native-test-app-0.0.1-dev.tgz | grep ignore
package/example/_gitignore
package/example/windows/_gitignore

[kelset]

tested locally, works as expected 👍 kind of surprised by this behaviour but I guess that's why in RN's template we have all the dotenv files as "_"