* Querying for changelists using @n,m syntax allows the Perforce server to execute queries using an optimized codepath. Attempt to query for code changes using this syntax by default (with an arbitrary lower bound for the range), and fallback to the legacy query syntax if we don't find any results.
* Use the -e argument when executing p4 changes commands to specify a minimum changelist number. This query syntax is more efficient than specifying a wildcard with revision range.
* Use PerforceUtils.CodeExtensions as the list of code extensions, to unify with UAT/Horde.
#preflight none
#jira UE-164680, UE-160465
[CL 22221689 by Edstub207 in ue5-main branch]
44b67593c9