Fix small bug with services set via --device-config

before:
```
  File "/home/alanrosenthal/code/fitbit/bumble/bumble/gatt.py", line 572, in __str__
    f'Descriptor(handle=0x{self.handle:04X}, '
  File "/home/alanrosenthal/code/fitbit/bumble/bumble/att.py", line 756, in read_value
    self.permissions & self.READ_REQUIRES_ENCRYPTION
TypeError: unsupported operand type(s) for &: 'str' and 'int'
```

bumble/att.py

@@ -23,11 +23,12 @@
 # Imports
 # -----------------------------------------------------------------------------
 from __future__ import annotations
+import functools
 import struct
 from pyee import EventEmitter
 from typing import Dict, Type, TYPE_CHECKING
 
-from bumble.core import UUID, name_or_number
+from bumble.core import UUID, name_or_number, get_dict_key_by_value
 from bumble.hci import HCI_Object, key_with_value
 from bumble.colors import color
 
@@ -725,11 +726,33 @@ class Attribute(EventEmitter):
     READ_REQUIRES_AUTHORIZATION = 0x40
     WRITE_REQUIRES_AUTHORIZATION = 0x80
 
+    PERMISSION_NAMES = {
+        READABLE: 'READABLE',
+        WRITEABLE: 'WRITEABLE',
+        READ_REQUIRES_ENCRYPTION: 'READ_REQUIRES_ENCRYPTION',
+        WRITE_REQUIRES_ENCRYPTION: 'WRITE_REQUIRES_ENCRYPTION',
+        READ_REQUIRES_AUTHENTICATION: 'READ_REQUIRES_AUTHENTICATION',
+        WRITE_REQUIRES_AUTHENTICATION: 'WRITE_REQUIRES_AUTHENTICATION',
+        READ_REQUIRES_AUTHORIZATION: 'READ_REQUIRES_AUTHORIZATION',
+        WRITE_REQUIRES_AUTHORIZATION: 'WRITE_REQUIRES_AUTHORIZATION',
+    }
+
+    @staticmethod
+    def string_to_permissions(permissions_str: str):
+        return functools.reduce(
+            lambda x, y: x | get_dict_key_by_value(Attribute.PERMISSION_NAMES, y),
+            permissions_str.split(","),
+            0,
+        )
+
     def __init__(self, attribute_type, permissions, value=b''):
         EventEmitter.__init__(self)
         self.handle = 0
         self.end_group_handle = 0
-        self.permissions = permissions
+        if isinstance(permissions, str):
+            self.permissions = self.string_to_permissions(permissions)
+        else:
+            self.permissions = permissions
 
         # Convert the type to a UUID object if it isn't already
         if isinstance(attribute_type, str):

bumble/device.py

@@ -999,7 +999,7 @@ class Device(CompositeEventEmitter):
                 new_characteristic = Characteristic(
                     uuid=characteristic["uuid"],
                     properties=characteristic["properties"],
-                    permissions=int(characteristic["permissions"], 0),
+                    permissions=characteristic["permissions"],
                     descriptors=descriptors,
                 )
                 characteristics.append(new_characteristic)

tests/gatt_test.py

@@ -37,10 +37,12 @@ from bumble.gatt import (
     Service,
     Characteristic,
     CharacteristicValue,
+    Descriptor,
 )
 from bumble.transport import AsyncPipeSink
 from bumble.core import UUID
 from bumble.att import (
+    Attribute,
     ATT_EXCHANGE_MTU_REQUEST,
     ATT_ATTRIBUTE_NOT_FOUND_ERROR,
     ATT_PDU,
@@ -861,6 +863,29 @@ async def async_main():
     await test_mtu_exchange()
 
 
+# -----------------------------------------------------------------------------
+def test_attribute_string_to_permissions():
+    assert Attribute.string_to_permissions('READABLE') == 1
+    assert Attribute.string_to_permissions('WRITEABLE') == 2
+    assert Attribute.string_to_permissions('READABLE,WRITEABLE') == 3
+
+
+# -----------------------------------------------------------------------------
+def test_charracteristic_permissions():
+    characteristic = Characteristic(
+        'FDB159DB-036C-49E3-B3DB-6325AC750806',
+        Characteristic.READ | Characteristic.WRITE | Characteristic.NOTIFY,
+        'READABLE,WRITEABLE',
+    )
+    assert characteristic.permissions == 3
+
+
+# -----------------------------------------------------------------------------
+def test_descriptor_permissions():
+    descriptor = Descriptor('2902', 'READABLE,WRITEABLE')
+    assert descriptor.permissions == 3
+
+
 # -----------------------------------------------------------------------------
 if __name__ == '__main__':
     logging.basicConfig(level=os.environ.get('BUMBLE_LOGLEVEL', 'INFO').upper())