chore: Minor changes to the excludeNonFlow mode and flow-typed libdef…

…s update script

This patch contains some additional flow type checking errors that have been caught
by the updated flow-typed definitions and the most recent flow version, and some
minor tweaks to the new excludeNonFlow mode.

- Applied fixes for new flow type checking errors
- Updated flow to 0.72.0 and Added npm script to update flow-typed definitions
- Do not collect flow coverage data for non-flow file in excludeNonFlow mode
- Added excludeNonFlow as false to default configs
- Added unit test for excludeNonFlow mode

__tests__/integrations/cli/__snapshots__/test-regression-issue-57.js.snap

@@ -3,7 +3,7 @@
 exports[`Fixed #57 - NaN in text report 1`] = `
 Object {
   "filteredStdout": Array [
-    "│ src/url.js │       flow │     0 % │     7 │       0 │ 7         │",
+    "│ src/url.js │       flow │     0 % │     9 │       0 │ 9         │",
   ],
   "stderr": "Flow Coverage 0% is below the required threshold 80%
 ",