MM-25261: Add 'include_deleted' parameter to get all channels API req… (#14721)

* MM-25261: Add 'include_deleted' parameter to get all channels API request.

* MM-25261: Adds test for deleted channels.

* MM-25261: Switches to single liner.

* MM-25261: Adhere to beta config setting for viewing archived channels.

* MM-25261: Test fix.

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/channel.go

@@ -687,6 +687,7 @@ func getAllChannels(c *Context, w http.ResponseWriter, r *http.Request) {
 	opts := model.ChannelSearchOpts{
 		NotAssociatedToGroup:   c.Params.NotAssociatedToGroup,
 		ExcludeDefaultChannels: c.Params.ExcludeDefaultChannels,
+		IncludeDeleted:         c.Params.IncludeDeleted,
 	}
 
 	channels, err := c.App.GetAllChannels(c.Params.Page, c.Params.PerPage, opts)