[13.x] Rename `CheckClientCredentials` middleware

[hafezdivandari]

This PR corrects the naming of the CheckClientCredentials and CheckClientCredentialsForAnyScope middlewares. As mentioned in this comment and this issue, the current naming is confusing and does not accurately reflect the functionality of these middlewares:

• The CheckClientCredentials class has been renamed to CheckToken, as it does not check client credentials but instead verifies whether the token is valid and has all the specified scopes.
• The CheckClientCredentialsForAnyScope class has been renamed to CheckTokenForAnyScope, as it does not check client credentials but verifies whether the token has any of the specified scopes.
• The CheckCredentials abstract class has been renamed to ValidateToken, as it does not check credentials but rather parses and validates the bearer token.

Summary

• CheckClientCredentials -> CheckToken
• CheckClientCredentialsForAnyScope -> CheckTokenForAnyScope
• CheckCredentials -> ValidateToken

Usage

Refer to the updated docs:

[taylorotwell]

Isn't the token the client's credentials?

[hafezdivandari]

@taylorotwell No, it works with any token, and that's exactly what makes its naming confusing.

[taylorotwell]

@hafezdivandari it's probably about time we think about releasing 13.x? Is there much more to do?

[hafezdivandari]

@taylorotwell there are 5 PRs in draft, the most important one is #1750 and #1762, we are waiting for @Sephster to merge the related bug fixes on oauth2-server package before Passport 13.x release.