End to bridge encryption implementation

So far this is passing my basic tests, but could use some testing from people
that are much more familiar with how this is supposed to work.

Refs #27

database/cryptostore.go

@@ -0,0 +1,97 @@
+package database
+
+import (
+	"database/sql"
+
+	log "maunium.net/go/maulogger/v2"
+
+	"maunium.net/go/mautrix/crypto"
+	"maunium.net/go/mautrix/id"
+)
+
+type SQLCryptoStore struct {
+	*crypto.SQLCryptoStore
+	UserID        id.UserID
+	GhostIDFormat string
+}
+
+var _ crypto.Store = (*SQLCryptoStore)(nil)
+
+func NewSQLCryptoStore(db *Database, userID id.UserID, ghostIDFormat string) *SQLCryptoStore {
+	return &SQLCryptoStore{
+		SQLCryptoStore: crypto.NewSQLCryptoStore(db.DB, db.dialect, "", "",
+			[]byte("maunium.net/go/mautrix-whatsapp"),
+			&cryptoLogger{db.log.Sub("CryptoStore")}),
+		UserID:        userID,
+		GhostIDFormat: ghostIDFormat,
+	}
+}
+
+func (store *SQLCryptoStore) FindDeviceID() id.DeviceID {
+	var deviceID id.DeviceID
+
+	query := `SELECT device_id FROM crypto_account WHERE account_id=$1`
+	err := store.DB.QueryRow(query, store.AccountID).Scan(&deviceID)
+	if err != nil && err != sql.ErrNoRows {
+		store.Log.Warn("Failed to scan device ID: %v", err)
+	}
+
+	return deviceID
+}
+
+func (store *SQLCryptoStore) GetRoomMembers(roomID id.RoomID) ([]id.UserID, error) {
+	query := `
+		SELECT user_id FROM mx_user_profile
+		WHERE room_id=$1
+			AND (membership='join' OR membership='invite')
+			AND user_id<>$2
+			AND user_id NOT LIKE $3
+	`
+
+	members := []id.UserID{}
+
+	rows, err := store.DB.Query(query, roomID, store.UserID, store.GhostIDFormat)
+	if err != nil {
+		return members, err
+	}
+
+	for rows.Next() {
+		var userID id.UserID
+		err := rows.Scan(&userID)
+		if err != nil {
+			store.Log.Warn("Failed to scan member in %s: %v", roomID, err)
+			return members, err
+		}
+
+		members = append(members, userID)
+	}
+
+	return members, nil
+}
+
+// TODO merge this with the one in the parent package
+type cryptoLogger struct {
+	int log.Logger
+}
+
+var levelTrace = log.Level{
+	Name:     "TRACE",
+	Severity: -10,
+	Color:    -1,
+}
+
+func (c *cryptoLogger) Error(message string, args ...interface{}) {
+	c.int.Errorfln(message, args...)
+}
+
+func (c *cryptoLogger) Warn(message string, args ...interface{}) {
+	c.int.Warnfln(message, args...)
+}
+
+func (c *cryptoLogger) Debug(message string, args ...interface{}) {
+	c.int.Debugfln(message, args...)
+}
+
+func (c *cryptoLogger) Trace(message string, args ...interface{}) {
+	c.int.Logfln(levelTrace, message, args...)
+}