ChangeScreen2: Auto-focus to submit button

After scoring a change with a maximum value in a radio group focus to
the submit button if it is enabled.  This allows committers to submit
a change with just Return/Enter/Space after posting Code-Review+2.

Change-Id: Ide28d62c24cfe7fd7e044d8b3b74ac5d246b8739
Split PGPEncryptedDataGenerator creation out into a utility method

Split the creation of PGPEncryptedDataGenerator out into a utility
method.  Inline the call to the open() method on the returned generator
rather than storing the generator in a temporary variable.

Suppress deprecation warnings caused by using methods that have been
deprecated in the new version of Bouncycastle that was introduced
recently.  We cannot yet replace the calls with the newer versions
because some Gerrit sites still use the older version of Bouncycastle.

Change-Id: I98f4b7c7bf8ab1ee74eb8bbc86b673d057d98e46
Merge "ChangeScreen2: Auto-focus to submit button"
Merge "Split PGPEncryptedDataGenerator creation out into a utility method"