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/channels/app/file_helper.go

@@ -25,7 +25,7 @@ func (a *App) removeInaccessibleContentFromFilesSlice(files []*model.FileInfo) (
 		return 0, nil
 	}
 
-	var firstInaccessibleFileTime int64 = 0
+	var firstInaccessibleFileTime int64
 	for _, file := range files {
 		if createAt := file.CreateAt; createAt < lastAccessibleFileTime {
 			file.MakeContentInaccessible()
@@ -143,7 +143,7 @@ func (a *App) getFilteredAccessibleFiles(files []*model.FileInfo, options filter
 			return files, 0, nil
 		}
 		if bounds.noAccessible() {
-			var firstInaccessibleFileTime int64 = 0
+			var firstInaccessibleFileTime int64
 			if lenFiles > 0 {
 				firstFileCreatedAt := files[0].CreateAt
 				lastFileCreatedAt := files[len(files)-1].CreateAt
@@ -194,7 +194,7 @@ func linearFilterFileList(fileList *model.FileInfoList, earliestAccessibleTime i
 // this is the slower fallback that is still safe
 // if we can not assume files are ordered by CreatedAt
 func linearFilterFilesSlice(files []*model.FileInfo, earliestAccessibleTime int64) ([]*model.FileInfo, int64) {
-	var firstInaccessibleFileTime int64 = 0
+	var firstInaccessibleFileTime int64
 	n := 0
 	for i := range files {
 		if createAt := files[i].CreateAt; createAt >= earliestAccessibleTime {