Update valid scopes for project_access_token and group_access_token

This updates the access token resources to support newly introduced scopes:

• ai_features
• k8s_proxy
• read_observability
• write_observability

See:

• https://docs.gitlab.com/ee/user/project/settings/project_access_tokens.html#scopes-for-a-project-access-token
• https://docs.gitlab.com/ee/user/group/settings/group_access_tokens.html#scopes-for-a-group-access-token
• https://docs.gitlab.com/ee/operations/tracing.html#create-an-access-token-and-enable-tracing