module/i3: fix regression in handling of persistent workspaces

bbd2394601 added support for ‘rename’
and ‘move’ events. In order to do that, it changed how workspace
events are matched against our internal workspace list: from string
comparing the workspace name, to checking i3/sway’s workspace ID
parameter.

This introduced a regression in our handling of persistent
workspaces. A persistent workspace is one that isn’t removed from the
bar when it’s deleted (empty, and switched away from) by i3/sway.

This concept doesn’t exist in i3/sway, but is something we’ve
added. Put simple, the way we do this is be keeping the workspace in
our list, even when i3/sway tells us it has been deleted.

However, at this point the workspace doesn’t have an ID anymore. And
the same is true at startup; when we initialize the persistent
workspaces, we only have their names. Not their IDs (since the
workspaces don’t actually exist yet).

To this the regression, we need to:

a) fallback to looking up workspaces by name. That is, if we fail to
  find one with a matching ID, try again using the workspace name. For
  _this_ to match, we also required the matched workspace to be a
  persistent workspace, with an ID < 0 (which essentially means the
  workspace doesn’t exist yet).

b) reset the ID to -1 when a persistent workspace is "deleted".

Closes #253

CHANGELOG.md

@@ -33,10 +33,13 @@
   `poll-interval` ([#241][241]).
 * battery: module was not thread safe.
 * dwl module reporting only the last part of the title ([#251][251])
+* i3/sway: regression; persistent workspaces shown twice
+  ([#253][253]).
 
 [239]: https://codeberg.org/dnkl/yambar/issues/239
 [241]: https://codeberg.org/dnkl/yambar/issues/241
 [251]: https://codeberg.org/dnkl/yambar/pulls/251
+[253]: https://codeberg.org/dnkl/yambar/issues/253
 
 
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