refactor: move util/fs under util/gitfs (#6618)

lib/manager/bundler/artifacts.spec.ts

lib/manager/bundler/artifacts.ts

lib/manager/bundler/extract.spec.ts

lib/manager/bundler/extract.ts

lib/manager/bundler/utils.ts

lib/manager/cargo/artifacts.ts

lib/manager/cocoapods/artifacts.ts

lib/manager/cocoapods/utils.ts

lib/manager/composer/artifacts.spec.ts

lib/manager/composer/artifacts.ts

lib/manager/composer/extract.spec.ts

lib/manager/composer/extract.ts

lib/manager/gomod/artifacts.ts

lib/manager/gradle-wrapper/artifacts.spec.ts

lib/manager/gradle-wrapper/artifacts.ts

lib/manager/gradle/index.spec.ts

lib/manager/gradle/index.ts

lib/manager/helm-requirements/extract.spec.ts

lib/manager/helm-requirements/extract.ts

lib/manager/maven/extract.ts