Use OIDC well-known configuration

[randomir]

With OIDC .well-known now available on Leap, we should simplify/generalize some auth URL resolvers:

dwave-cloud-client/dwave/cloud/auth/flows.py

Lines 309 to 329 in d9c0dbf

	# note: in the future we might want to replace these url resolvers with a
	# OpenID Provider Metadata server query
	@staticmethod
	def _infer_auth_endpoint(leap_api_endpoint: str) -> str:
	return urljoin(leap_api_endpoint, '/leap/openid/authorize')
	@staticmethod
	def _infer_token_endpoint(leap_api_endpoint: str) -> str:
	return urljoin(leap_api_endpoint, '/leap/openid/token')
	@staticmethod
	def _infer_revocation_endpoint(leap_api_endpoint: str) -> str:
	return urljoin(leap_api_endpoint, '/leap/openid/revoke_token/')
	@staticmethod
	def _infer_leap_success_uri(leap_api_endpoint: str) -> str:
	return urljoin(leap_api_endpoint, '/leap/openid/success/')
	@staticmethod
	def _infer_leap_error_uri(leap_api_endpoint: str) -> str:
	return urljoin(leap_api_endpoint, '/leap/openid/error/')

Note: consider caching the configuration and/or individual auth URLs.