[kubectl] Implement azure auth module in external credential provider

[weinong]

As upstream community (sig-auth) is discussing to remove all the auth modules except oidc and exec in kubectl eventually, the ask is to migrate the azure auth module to KEP: External credential provider which is available starting at v1.11 (beta).

This opportunity gives us a solution to implement more features (non-interactive login mode) and client side bug fixes with greater flexibility as it's no longer tied to in-tree kubectl.

[ritazh]

remove all the auth modules except oidc and exec in kubectl eventually

this will be discussed at the next sig-auth meeting. tentatively the existing azure auth module will be deprecated in 1.19, removed in 1.22

[ritazh]

As discussed in today's sig-auth meeting, deprecation of the in tree client auth credential provider won't happen until one year after the external credential provider goes to GA.