Expose public/ API as submodule (#23345)

* model -> public/model

* plugin -> public/plugin

* public/model/utils -> public/utils

* platform/shared/mlog -> public/shared/mlog

* platform/shared/i18n -> public/shared/i18n

* platform/shared/markdown -> public/shared/markdown

* platform/services/timezones -> public/shared/timezones

* channels/einterfaces -> einterfaces

* expose public/ submodule

* go mod tidy

* .github: cache-dependency-path, setup-go-work

* modules-tidy for public/ too

* remove old gomodtidy

server/public/model/channel_list.go

@@ -0,0 +1,56 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+type ChannelList []*Channel
+
+func (o *ChannelList) Etag() string {
+
+	id := "0"
+	var t int64 = 0
+	var delta int64 = 0
+
+	for _, v := range *o {
+		if v.LastPostAt > t {
+			t = v.LastPostAt
+			id = v.Id
+		}
+
+		if v.UpdateAt > t {
+			t = v.UpdateAt
+			id = v.Id
+		}
+
+	}
+
+	return Etag(id, t, delta, len(*o))
+}
+
+type ChannelListWithTeamData []*ChannelWithTeamData
+
+func (o *ChannelListWithTeamData) Etag() string {
+
+	id := "0"
+	var t int64 = 0
+	var delta int64 = 0
+
+	for _, v := range *o {
+		if v.LastPostAt > t {
+			t = v.LastPostAt
+			id = v.Id
+		}
+
+		if v.UpdateAt > t {
+			t = v.UpdateAt
+			id = v.Id
+		}
+
+		if v.TeamUpdateAt > t {
+			t = v.TeamUpdateAt
+			id = v.Id
+		}
+	}
+
+	return Etag(id, t, delta, len(*o))
+}