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

• [x] Pull request is created against the dev branch
• [x] 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
• [x] I have added necessary documentation (if appropriate)