Add token endpoint auth method to the tokenURL in the securitySchemes

[mcrobbj]

Currently there is no way to define the token endpoint auth method, tooling just defaults to client_secret_post
By adding authMethod to the tokenURL in the securitySchemes so it aligns with Oauth spec would tooling supports more than just client secret post. Could this be added to v3.2.0-dev?

securitySchemes:
bearerAuth: # arbitrary name for the security scheme
description: This is the endcode JWT Access token
type: http
scheme: bearer
bearerFormat: string
oauthAuthCode:
description: Auth Code RFC8725 compliant
type: oauth2
flows:
authorizationCode:
authorizationUrl: 'https://oauth.simple.api/authorization'
tokenUrl: 'https://oauth.simple.api/token'
authMethod: client_secret_jwt
scopes:
myscope: myScope

where authMethoid is one of:

• client_secret_post
• client_secret_jwt
• private_key_jwt
• none
• tls_client_auth
• self_signed_tls_client_auth

The tooling seems to default to client_secret_post at the moment