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/context/repo.go

@@ -734,7 +734,7 @@ func RepoAssignment(ctx *Context) (cancel context.CancelFunc) {
 		ctx.Data["GoDocDirectory"] = prefix + "{/dir}"
 		ctx.Data["GoDocFile"] = prefix + "{/dir}/{file}#L{line}"
 	}
-	return
+	return cancel
 }
 
 // RepoRefType type of repo reference
@@ -1001,7 +1001,7 @@ func RepoRefByType(refType RepoRefType, ignoreNotExistErr ...bool) func(*Context
 			return
 		}
 		ctx.Data["CommitsCount"] = ctx.Repo.CommitsCount
-		return
+		return cancel
 	}
 }