[Connector Builder] Handle dot notation of config values in auth

[lmossman]

Context

The YAML -> UI conversion logic currently enforces that authorization components use user-input values for secret fields like api_token.

However, this currently is only checking that values are of the form config['var'], even though config.var is also valid syntax.

Acceptance Criteria

• Update the auth / user input override conversion logic to properly handle config values using the dot format