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/asymkey/ssh_key_test.go

@@ -317,7 +317,7 @@ func TestFromOpenSSH(t *testing.T) {
 			td := t.TempDir()
 
 			data := []byte("hello, ssh world")
-			dataPath := write(t, []byte(data), td, "data")
+			dataPath := write(t, data, td, "data")
 
 			privPath := write(t, []byte(tt.priv), td, "id")
 			write(t, []byte(tt.pub), td, "id.pub")
@@ -372,14 +372,14 @@ func TestToOpenSSH(t *testing.T) {
 			td := t.TempDir()
 
 			data := []byte("hello, ssh world")
-			write(t, []byte(data), td, "data")
+			write(t, data, td, "data")
 
 			armored, err := sshsig.Sign([]byte(tt.priv), bytes.NewReader(data), "file")
 			if err != nil {
 				t.Fatal(err)
 			}
 
-			sigPath := write(t, []byte(armored), td, "oursig")
+			sigPath := write(t, armored, td, "oursig")
 
 			// Create an allowed_signers file with two keys to check against.
 			allowedSigner := "test@rekor.dev " + tt.pub + "\n"