floss: Complete BTIF to Floss GATT attribute type conversions

Fix previously incomplete GATT attribute type conversions from the
Bluetooth Interface to Floss, including correctly setting GATT
attribute permissions.

Bug: 328812649
Test: m -j && manually with btclient:
Create a GATT attribute with non-null permissions, and observe they
remain non-zero after the parent service has been added.
Flag: Exempt, Floss-only change

Change-Id: I2a1a681361b56a0ed4c2331bfe104c656a90f5c3