mapclient: Inline MapUtils

With the removal of `setMnsService`, MapUtils doesn't bring a
lot of value. All the utility methods are called once and the
condition in `sendMessageType` is duplicated at the call site.

So MapUtils is removed and all of it's methods inlined.

Bug: 319112725
Test: m Bluetooth BluetoothInstrumentationTests
Flag: Exempt, mechanical refactor
Change-Id: Ib12d4a67cfe8d3ebaced32feaa4ea84e42d8d0a4