Add GetSystemPropertyUint32Base

Yes I assumed the int could be written as hexa in properties.
Yes I merged a change adding an hexa property
Yes I broke multiples devices
ヾ(_ _。）

Breakage was happening when you set these properties using hexa num
  bluetooth.l2cap.le.credit_default.value
  bluetooth.l2cap.le.credit_threshold.value

Dirty-cherry because of include conflict in l2c_api.cc

Bug: 263323082
Test: atest net_test_osi
Merged-In: Ie58c1bc0d637fc0fabd9797813187d1897c0df51
(cherry picked from commit 03ca4858)
Change-Id: Ib9d65164728254ead696187793b01151d04ee469