feat(workspaces): change sorting order of the workspace list

[rodrimaia]

changes to the sorting order of the workspace list. The new sorting order is as follows:

1. First, display workspaces that are currently running.
2. Next, sort by user_name.
3. Finally, sort by last_used_at in descending order.

That order was suggested in this conversation: #7590 (review).

[mtojek]

Let's have a second pair of backend eyes on this PR so that we can be sure that we do not need to mangle with database queries instead.

[rodrimaia]

@mtojek @johnstcn using table tests now

[mtojek]

👍

[mtojek]

LGTM, but CI complains about some tests:

=== FAIL: coderd TestSortWorkspaces/then_sort_by_last_used_at_(recent_first) (0.00s)
    workspaces_internal_test.go:173: 
        	Error Trace:	C:/a/coder/coder/coderd/workspaces_internal_test.go:173
        	Error:      	Not equal: 
        	            	expected: []string{"running-userA3", "running-userA2", "running-userA"}
        	            	actual  : []string{"running-userA3", "running-userA", "running-userA2"}
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -2,4 +2,4 @@
        	            	  (string) (len=14) "running-userA3",
        	            	- (string) (len=14) "running-userA2",
        	            	- (string) (len=13) "running-userA"
        	            	+ (string) (len=13) "running-userA",
        	            	+ (string) (len=14) "running-userA2"
        	            	 }
        	Test:       	TestSortWorkspaces/then_sort_by_last_used_at_(recent_first)
        	Messages:   	then sort by last used at (recent first)