v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/plugin/checker/internal/version/comments.go

@@ -0,0 +1,22 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package version
+
+import (
+	"regexp"
+	"strings"
+)
+
+var versionCommentRE = regexp.MustCompile(`^Minimum server version: (\d+\.\d+(?:\.\d+[\w-]*)?)$`)
+
+func ExtractMinimumVersionFromComment(s string) string {
+	lines := strings.Split(strings.TrimSpace(s), "\n")
+	if len(lines) > 0 {
+		lastLine := lines[len(lines)-1]
+		if m := versionCommentRE.FindStringSubmatch(lastLine); len(m) >= 1 {
+			return m[1]
+		}
+	}
+	return ""
+}