Excludes remote channels from channel search (#28708)

* Excludes remote channels from channel search

This is done through a new body parameter in the SearchAllChannels
endpoint that allows to search for local only channels, which are
either channels that are shared but marked as homed locally, or
channels that are not shared at all.

* fix lint

* Fix tests

---------

Co-authored-by: Caleb Roseland <caleb@calebroseland.com>

server/channels/api4/channel.go

@@ -1299,6 +1299,7 @@ func searchAllChannels(c *Context, w http.ResponseWriter, r *http.Request) {
 		ExcludeGroupConstrained:  props.ExcludeGroupConstrained,
 		ExcludePolicyConstrained: props.ExcludePolicyConstrained,
 		IncludeSearchById:        props.IncludeSearchById,
+		ExcludeRemote:            props.ExcludeRemote,
 		Public:                   props.Public,
 		Private:                  props.Private,
 		IncludeDeleted:           includeDeleted,

server/channels/api4/channel_test.go

@@ -1696,7 +1696,7 @@ func TestSearchArchivedChannels(t *testing.T) {
 }
 
 func TestSearchAllChannels(t *testing.T) {
-	th := Setup(t).InitBasic()
+	th := setupForSharedChannels(t).InitBasic()
 	th.LoginSystemManager()
 	defer th.TearDown()
 	client := th.Client
@@ -1737,6 +1737,29 @@ func TestSearchAllChannels(t *testing.T) {
 	})
 	require.NoError(t, err)
 
+	// share the open and private channels, one homed locally and the
+	// other remotely
+	sco := &model.SharedChannel{
+		ChannelId: openChannel.Id,
+		TeamId:    openChannel.TeamId,
+		Home:      true,
+		ShareName: "testsharelocal",
+		CreatorId: th.BasicChannel.CreatorId,
+	}
+	_, scoErr := th.App.ShareChannel(th.Context, sco)
+	require.NoError(t, scoErr)
+
+	scp := &model.SharedChannel{
+		ChannelId: privateChannel.Id,
+		TeamId:    privateChannel.TeamId,
+		Home:      false,
+		RemoteId:  model.NewId(),
+		ShareName: "testshareremote",
+		CreatorId: th.BasicChannel.CreatorId,
+	}
+	_, scpErr := th.App.ShareChannel(th.Context, scp)
+	require.NoError(t, scpErr)
+
 	testCases := []struct {
 		Description        string
 		Search             *model.ChannelSearch
@@ -1847,6 +1870,11 @@ func TestSearchAllChannels(t *testing.T) {
 			&model.ChannelSearch{Term: "SearchAllChannels", ExcludeGroupConstrained: true},
 			[]string{openChannel.Id, privateChannel.Id},
 		},
+		{
+			"Search for local only channels",
+			&model.ChannelSearch{Term: "SearchAllChannels", ExcludeRemote: true},
+			[]string{openChannel.Id, groupConstrainedChannel.Id},
+		},
 	}
 	for _, testCase := range testCases {
 		t.Run(testCase.Description, func(t *testing.T) {