[fidl] Format all the FIDL files

This CL applies fidl_format to all the FIDL files that are not used to
test the parser.

Test: No behavior change
Change-Id: I6e83e78e64ca7ec620d021298c50dcf848102176

[netstack] Check in API definition for network connectivity service.

Change-Id: I10e4b50eeb0587b6a45b8b4716ef4fef0a818d09
Tested:
- fx full-build this patch and https://fuchsia-review.googlesource.com/c/garnet/+/163768
- fx run-test netstack_connectivity_test