Add support for parsing externals with revisions as dates
That MR adds support for properly processing external definitions using dates as revision format, see example below:
svn://svn.code.sf.net/p/contools/contools/trunk/Scripts/__init__@{2021-03-01T02:02:20Z} contools/Scripts/__init__
svn://svn.code.sf.net/p/contools/contools/trunk/Scripts/Tools/__init__@{2021-03-01T02:02:20Z} contools/Scripts/Tools/__init__
Related to #4727 (closed)