NetworkConfig: Default to autoconnect and show connecting

This CL fixes two minor network config UI issues with
--network-settings-config:

* Adds "Connecting" to the dialog while connecting
* Sets 'AutoConnect' to true unless prohibited by policy
  (matches current UI behavior)

Bug: 380937
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I5b58d9080f555431f23eba1ffa0c3806da2a8c63
Reviewed-on: https://chromium-review.googlesource.com/801917
Reviewed-by: Toni Barzic <[email protected]>
Commit-Queue: Steven Bennetts <[email protected]>
Cr-Commit-Position: refs/heads/master@{#520771}
7 files changed