Account management - Improve user creation for integration with Okta and JIRA

1) Add first name and last name fields

• Make them required
• If user already exists, just ignore these fields

Downstream in JIRA and Okta, the newly created users have no real names.  When Support creates Technical Contacts they require the user's full name and email.

2) Do not allow duplicate identities and treat UID/email as case-insensitive (e.g. grant.spradlin@nuxeo.com and Grant.Spradlin@nuxeo.com are the same identities and emails are never case-sensitive)

• When searching for an existing user, do not treat the search as case-sensitive
• When creating a new user, make the UID/email lower case

The case-sensitivity allows duplicate users to be created in Connect for the same identity, when downstream in Okta the UID/email is case-insensitive and there is only one identity.