feat: refactor firefox get master key retrieval and decryption functions.

[moonD4rk]

Proposed changes

Process masterkey when init firefox instance

// GetMasterKey returns master key of Firefox. from key4.db
func (f *Firefox) GetMasterKey() ([]byte, error) {
	tempFilename := item.FirefoxKey4.TempFilename()

	// Open and defer close of the database.
	keyDB, err := sql.Open("sqlite", tempFilename)
	if err != nil {
		return nil, fmt.Errorf("open key4.db error: %w", err)
	}
	defer os.Remove(tempFilename)
	defer keyDB.Close()

	globalSalt, metaBytes, err := queryMetaData(keyDB)
	if err != nil {
		return nil, fmt.Errorf("query metadata error: %w", err)
	}

	nssA11, nssA102, err := queryNssPrivate(keyDB)
	if err != nil {
		return nil, fmt.Errorf("query NSS private error: %w", err)
	}

	return processMasterKey(globalSalt, metaBytes, nssA11, nssA102)
}

Checklist

• Pull request is created against the dev branch
• All checks passed (lint, unit, build tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)