Add OAuth2 scope sources for access review, slack, googleworkspace

Each module that initiates an OAuth2 flow now declares its scopes
in its own package instead of duplicating them in the frontend or
in shared connector config:

- pkg/accessreview/drivers: per-provider scopes for the access
  review drivers
- pkg/slack: scopes for the compliance page integration
- pkg/iam/scim/bridge/provider/googleworkspace: scopes for the
  SCIM provisioning bridge

These constants are surfaced to the frontend via GraphQL fields
so the frontend never hardcodes scope strings.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/slack/oauth2_scopes.go

@@ -0,0 +1,26 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package slack
+
+var (
+	// OAuth2Scopes are the Slack OAuth2 scopes required by the compliance
+	// page integration. The compliance page joins channels and posts
+	// messages on behalf of the connected workspace.
+	OAuth2Scopes = []string{
+		"chat:write",
+		"channels:join",
+		"incoming-webhook",
+	}
+)