Add boilerplate.

.flowconfig

@@ -0,0 +1,75 @@
+[ignore]
+; We fork some components by platform
+.*/*[.]android.js
+
+; Ignore "BUCK" generated dirs
+<PROJECT_ROOT>/\.buckd/
+
+; Ignore polyfills
+node_modules/react-native/Libraries/polyfills/.*
+
+; These should not be required directly
+; require from fbjs/lib instead: require('fbjs/lib/warning')
+node_modules/warning/.*
+
+; Flow doesn't support platforms
+.*/Libraries/Utilities/LoadingView.js
+
+[untyped]
+.*/node_modules/@react-native-community/cli/.*/.*
+
+[include]
+
+[libs]
+node_modules/react-native/Libraries/react-native/react-native-interface.js
+node_modules/react-native/flow/
+
+[options]
+emoji=true
+
+esproposal.optional_chaining=enable
+esproposal.nullish_coalescing=enable
+
+module.file_ext=.js
+module.file_ext=.json
+module.file_ext=.ios.js
+
+munge_underscores=true
+
+module.name_mapper='^react-native$' -> '<PROJECT_ROOT>/node_modules/react-native/Libraries/react-native/react-native-implementation'
+module.name_mapper='^react-native/\(.*\)$' -> '<PROJECT_ROOT>/node_modules/react-native/\1'
+module.name_mapper='^[./a-zA-Z0-9$_-]+\.\(bmp\|gif\|jpg\|jpeg\|png\|psd\|svg\|webp\|m4v\|mov\|mp4\|mpeg\|mpg\|webm\|aac\|aiff\|caf\|m4a\|mp3\|wav\|html\|pdf\)$' -> '<PROJECT_ROOT>/node_modules/react-native/Libraries/Image/RelativeImageStub'
+
+suppress_type=$FlowIssue
+suppress_type=$FlowFixMe
+suppress_type=$FlowFixMeProps
+suppress_type=$FlowFixMeState
+
+suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe\\($\\|[^(]\\|(\\(<VERSION>\\)? *\\(site=[a-z,_]*react_native\\(_ios\\)?_\\(oss\\|fb\\)[a-z,_]*\\)?)\\)
+suppress_comment=\\(.\\|\n\\)*\\$FlowIssue\\((\\(<VERSION>\\)? *\\(site=[a-z,_]*react_native\\(_ios\\)?_\\(oss\\|fb\\)[a-z,_]*\\)?)\\)?:? #[0-9]+
+suppress_comment=\\(.\\|\n\\)*\\$FlowExpectedError
+
+[lints]
+sketchy-null-number=warn
+sketchy-null-mixed=warn
+sketchy-number=warn
+untyped-type-import=warn
+nonstrict-import=warn
+deprecated-type=warn
+unsafe-getters-setters=warn
+inexact-spread=warn
+unnecessary-invariant=warn
+signature-verification-failure=warn
+deprecated-utility=error
+
+[strict]
+deprecated-type
+nonstrict-import
+sketchy-null
+unclear-type
+unsafe-getters-setters
+untyped-import
+untyped-type-import
+
+[version]
+^0.105.0