rename "Your data source" to "Data source" page
This page was meant to be named "Data source" in the previous PR [0].
I just made a mistake by naming it wrongly.
[0]: https://github.com/grafana/grafana/pull/66813/files
* fix: use the correct URL for editing datasource dashboards
* feat: show the Datasource/Dashboards page under Connections as well
* refactor: remove unnecessary `useNavModel()` utility
* feat: add a utility for creating the nav-model for DS settings tabs
* refactor: use nav-model crating utility in Edit Datasource