Add more linters to improve code readability (#19989)

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

modules/git/repo_compare.go

@@ -132,7 +132,7 @@ type lineCountWriter struct {
 func (l *lineCountWriter) Write(p []byte) (n int, err error) {
 	n = len(p)
 	l.numLines += bytes.Count(p, []byte{'\000'})
-	return
+	return n, err
 }
 
 // GetDiffNumChangedFiles counts the number of changed files
@@ -177,7 +177,7 @@ func (repo *Repository) GetDiffShortStat(base, head string) (numFiles, totalAddi
 	if err != nil && strings.Contains(err.Error(), "no merge base") {
 		return GetDiffShortStat(repo.Ctx, repo.Path, base, head)
 	}
-	return
+	return numFiles, totalAdditions, totalDeletions, err
 }
 
 // GetDiffShortStat counts number of changed files, number of additions and deletions
@@ -231,7 +231,7 @@ func parseDiffStat(stdout string) (numFiles, totalAdditions, totalDeletions int,
 			return 0, 0, 0, fmt.Errorf("unable to parse shortstat: %s. Error parsing NumDeletions %v", stdout, err)
 		}
 	}
-	return
+	return numFiles, totalAdditions, totalDeletions, err
 }
 
 // GetDiffOrPatch generates either diff or formatted patch data between given revisions