Merge request Authors are not set in userCatalogue

[alkalinan]

In GHModelImporter, importing a user, from importMergeResquestAuthor: does not add it to the userCatalogue property of the importer. This can be fix by changing importUser: last lines. Note that API of user imports can be generic to all importer (future works)

importUser: aUserID

	| result userResult |
	(self glhModel allWithType: GLHUser)
		detect: [ :user | user id = aUserID ]
		ifFound: [ :user | ^ user ].
	('Import user: ' , aUserID printString) recordInfo.
	result := self repoApi user: aUserID.
	userResult := self parseUserResult: result.
	userResult := self glhModel add: userResult unless: self blockOnIdEquality.
	"ADD TO CATALOGUE"
        userCatalogue addUser: userResult.
	^ userResult