file permissions for creating files should be constants and consistent

[bdw617]

Describe what should be investigated or refactored

os.WriteFile() is called with various permission masks, should standardize them with a constant

here's the output from `go sec ./...`
[/zarf/src/pkg/packager/common.go:378] - G306 (CWE-276): Expect WriteFile permissions to be 0600 or less (Confidence: HIGH, Severity: MEDIUM)
    377:                        message.Debug(status)
  > 378:                        if err := os.WriteFile(path, chunk, 0644); err != nil {
    379:                                return fmt.Errorf("unable to write the file %s: %w", path, err)

Here are examples of the inconsistencies:
we're using at least 0640, 0600, 0644
unclear if we ever need to get group or other access.

os.MkdirAll() os.Mkdir() os.Chmod() should all be consistent.

➜  zarf git:(main) ✗ find . -name "*.go" | xargs grep os.WriteFile
./src/cmd/prepare.go:                   err = os.WriteFile(fileName, []byte(processedText), 0640)
./src/cmd/tools/zarf.go:                if err := os.WriteFile("tls.ca", pki.CA, 0644); err != nil {
./src/cmd/tools/zarf.go:                if err := os.WriteFile("tls.crt", pki.Cert, 0644); err != nil {
./src/cmd/tools/zarf.go:                if err := os.WriteFile("tls.key", pki.Key, 0600); err != nil {
./src/cmd/tools/zarf.go:                if err := os.WriteFile(prvKeyFileName, keyBytes.PrivateBytes, 0600); err != nil {
./src/cmd/tools/zarf.go:                if err := os.WriteFile(pubKeyFileName, keyBytes.PublicBytes, 0644); err != nil {
./src/pkg/packager/common.go:                   if err := os.WriteFile(path, chunk, 0644); err != nil {
./src/pkg/utils/io.go:  return os.WriteFile(path, []byte(text), 0600)
./src/pkg/utils/image.go:       return os.WriteFile(indexPath, indexJSONBytes, 0600)
./src/pkg/utils/json.go:        return os.WriteFile(path, data, 0644)
./src/pkg/utils/yaml.go:        return os.WriteFile(path, content, perm)

[Noxsios]

Fixed in #2235 by src/pkg/utils/helpers/io.go