feat(enterprise): implement organization "disable workspace sharing" option (#21376)

Adds a per-organization setting to disable workspace sharing. When enabled,
all existing workspace ACLs in the organization are cleared and the workspace
ACL mutation API endpoints return `403 Forbidden`.

This complements the existing site-wide `--disable-workspace-sharing` flag by
providing more granular control at the organization level.

Closes https://github.com/coder/internal/issues/1073 (part 2)

---------

Co-authored-by: Steven Masley <Emyrk@users.noreply.github.com>

coderd/database/queries/workspaces.sql

@@ -947,6 +947,15 @@ SET
 WHERE
 	id = @id;
 
+-- name: DeleteWorkspaceACLsByOrganization :exec
+UPDATE
+	workspaces
+SET
+	group_acl = '{}'::jsonb,
+	user_acl = '{}'::jsonb
+WHERE
+	organization_id = @organization_id;
+
 -- name: GetRegularWorkspaceCreateMetrics :many
 -- Count regular workspaces: only those whose first successful 'start' build
 -- was not initiated by the prebuild system user.