Support email address aggregation for shadowed users

When displaying Commit authors in the commit list, Stash searches the name by using the git email that was used to commit.

When there are multiple user directories, Stash user management checks for the same usernames and uses the information from the directory with higher priority.

Two account may have the same username but different email and display name. If the commit author email matches one of the account in the lower priority directory (which is not displayed in the list of users), it will display the name from the lower priority directory.

Steps to replicate:

1. Create an account in Stash with the following details (where the internal directory has a lower precedence)
   • User Name = testaccount
   • Name = Stash User
   • Email = stashtest@test.com
2. Create an account in Jira with the following details (where the JIRA directory has a higher precedence)
   • User Name = testaccount
   • Name = Jira User
   • Email = jiratest@test.com
3. Link Jira User directory in Stash. Set it as higher priority than Stash Internal Directory.
4. Perform a commit with email address stashtest@test.com
5. The author name is shown as "Stash User" in Stash. Clicking on the user name would link it to the account page of "Jira User".
6. "Stash User" is not listed in the list of user because "Jira User" is shown as the name for username "testaccount"

Workaround

Configure a mailmap for the email address