[all] Switch to pedantic analysis rules (flutter#2300)

Switches our out of date fork of Flutter's analysis rules to the
pedantic package. In order to make this an easy change to initially land
and then incrementally enable, any existing non-trivial lints have just
been ignored within their respective packages instead of being fixed.

Also adds a global lint for missing public DartDocs. Like the pedantic
lints, this is ignored in packages that are already failing it.

analysis_options.yaml

@@ -0,0 +1,11 @@
+# This is a temporary file to allow us to land a new set of linter rules in a
+# series of manageable patches instead of one gigantic PR. It disables some of
+# the new lints that are already failing on this plugin, for this plugin. It
+# should be deleted and the failing lints addressed as soon as possible.
+
+include: ../../analysis_options.yaml
+
+analyzer:
+  errors:
+    public_member_api_docs: ignore
+    unawaited_futures: ignore