feat(jans-config-api): User endpoint to expose custom attributes at root level

[pujavs]

Requirement: Currently the fields mail, displayName, jansStatus, userPassword, givenName in customAttributes array.
These need to be made available directly in json as this will be helpful for UI developers as these fields will be mandatory on UI.

example

{ "dn": "inum=203008f1-dc3e-41ee-a546-d7a2aa45f6ab,ou=people,o=jans", "userId": "admin5", "mail": "admin4@jans-ui.jans.io", "displayName": "Default Admin User", "jansStatus": "active", "userPassword": "secret123", "givenName" :"Admin", "createdAt": "2022-05-14T16:35:27", "baseDn": "inum=c8791801-4372-42b9-a53f-0990b79f62c4,ou=people,o=jans", "customAttributes": [{...}] }

[pujavs]

Code merged in main 1351

[pujavs]

New Requirement:
For ease in handling api response at UI side can we please have inum directly in json object of response (not inside customAttributes array)

for example:

{
"dn": "inum=265e952a-60b5-4e2b-acf7-b0b2412bbb3f,ou=people,o=jans",
"userId": "admin",
"customAttributes": [{...},..],
"customObjectClasses": ["top", "jansCustomPerson"],
"mail": "admin@admin-ui-test.gluu.org",
"displayName": "Default Admin User",
"jansStatus": "active",
"givenName": "Admin",
"baseDn": "inum=265e952a-60b5-4e2b-acf7-b0b2412bbb3f,ou=people,o=jans",
"inum": "265e952a-60b5-4e2b-acf7-b0b2412bbb3f"
}