MM-52532: Fix golangci warnings (#23709)

https://mattermost.atlassian.net/browse/MM-52532

- Replace golint with revive
- Add makezero linter
- Fix all the required linter failures

Some issues in enterprise and public modules
are yet to be fixed. We send this to expediate things.

server/public/model/channel_list.go

@@ -8,8 +8,8 @@ type ChannelList []*Channel
 func (o *ChannelList) Etag() string {
 
 	id := "0"
-	var t int64 = 0
-	var delta int64 = 0
+	var t int64
+	var delta int64
 
 	for _, v := range *o {
 		if v.LastPostAt > t {
@@ -32,8 +32,8 @@ type ChannelListWithTeamData []*ChannelWithTeamData
 func (o *ChannelListWithTeamData) Etag() string {
 
 	id := "0"
-	var t int64 = 0
-	var delta int64 = 0
+	var t int64
+	var delta int64
 
 	for _, v := range *o {
 		if v.LastPostAt > t {