Improve authenticator name and display name validation for user defined authenticators

[Thisara-Welmilla]

Description

Issue:

• Provide API for the new custom authentication management #21216

Following improvements need to be done to the custom authentication management.

1. Addressing Naming Conflicts for User-Defined and future System-Defined Authenticators
   Currently, for user-defined authenticators, it is checking for any conflict with system-defined names making authenticator name unique.
   The reqirement is to have unique identifier for the amr values. However, with the implementation so far, if a custom authenticator is created with the name whatsappAuthenticator and we later introduce a system authenticator with the same name, it would result in a conflict. There improve authenticator name regex validation to check whether authenticator name start with custom- prefix with atleast three charactors.
2. In addtion to above validate authenticator name uniqueness across both local and federared authenticator names.
3. Improve display name validation to check whether it has atleast three charactors.

Version

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