url handler downloads

Summary:
Adding support for downloading archived Flipper data using a URL handler.
A URL looks like `flipper://import/?url=` and will download the file specified in the url param. While downloading the file, a spinner is shown in the app's titlebar.

Reviewed By: jknoxville

Differential Revision: D14262763

fbshipit-source-id: 6538fc78c07a48cef7b71b3f7bdbcb712d054593

flow-typed/npm/query-string_v6.x.x.js

@@ -0,0 +1,33 @@
+// flow-typed signature: 9096718d5c8abc7d9ae9aadbe0ce565a
+// flow-typed version: 6d8676cf5a/query-string_v6.x.x/flow_>=v0.32.x
+
+declare module 'query-string' {
+  declare type ArrayFormat = 'none' | 'bracket' | 'index'
+  declare type ParseOptions = {|
+    arrayFormat?: ArrayFormat,
+  |}
+
+  declare type StringifyOptions = {|
+    arrayFormat?: ArrayFormat,
+    encode?: boolean,
+    strict?: boolean,
+    sort?: false | <A, B>(A, B) => number,
+  |}
+
+  declare type ObjectParameter = string | number | boolean | null | void;
+
+  declare type ObjectParameters = {
+    [string]: ObjectParameter | $ReadOnlyArray<ObjectParameter>
+  }
+
+  declare type QueryParameters = {
+    [string]: string | Array<string> | null
+  }
+
+  declare module.exports: {
+    extract(str: string): string,
+    parse(str: string, opts?: ParseOptions): QueryParameters,
+    parseUrl(str: string, opts?: ParseOptions): { url: string, query: QueryParameters },
+    stringify(obj: ObjectParameters, opts?: StringifyOptions): string,
+  }
+}