GitLab for Slack app support for multiple workspaces for Self-Managed and Dedicated

Proposal

Some organisations make use of multiple workspace. Currently Slack notifications can accommodate this however with the existing implementation of GitLab for Slack it is only possible to configure a single instance wide workspace.

Looking at the Slack Integration Planning epic it seems there are no plans to support using multiple workspaces.

Since slack notification integration is being depreciated with plans to migrate to Slack app by GitLab v17 this will effectively render this unusable for these customers.

This proposal is to consider adding support for multiple workspaces.

What success looks like

Organisation that make use of multiple federated workspaces are able to make use of GitLab for Slack.