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)

models/organization/team.go

@@ -185,7 +185,7 @@ func (t *Team) GetUnitNames() (res []string) {
 	for _, u := range t.Units {
 		res = append(res, unit.Units[u.Type].NameKey)
 	}
-	return
+	return res
 }
 
 // GetUnitsMap returns the team units permissions
@@ -226,7 +226,7 @@ func (t *Team) GetRepositoriesCtx(ctx context.Context) (err error) {
 	t.Repos, err = GetTeamRepositories(ctx, &SearchTeamRepoOptions{
 		TeamID: t.ID,
 	})
-	return
+	return err
 }
 
 // GetMembersCtx returns paginated members in team of organization.