Move TypeConverter into a shared library

This will be needed for the default implementation of the audio HAL
in TREBLE for parsing supported formats etc. provided by HAL in
a form of string literals.

As a bonus, remove some hand-written type conversions in AudioFlinger
used in dumps.

Example changes in the dump output:

   HAL format: 0x1 (pcm16) ==> HAL format: 0x1 (AUDIO_FORMAT_PCM_16_BIT)
   Processing format: 0x5 (pcmfloat) ==> Processing format: 0x5 (AUDIO_FORMAT_PCM_FLOAT)
   Output device: 0x2 (SPEAKER) ==> Output device: 0x2 (AUDIO_DEVICE_OUT_SPEAKER)
   Input device: 0 (NONE) ==> Input device: 0 (AUDIO_DEVICE_NONE)
   AudioStreamOut: 0x... flags 0x6 (PRIMARY|FAST) ==>
       AudioStreamOut: 0x... flags 0x6 (AUDIO_OUTPUT_FLAG_PRIMARY|AUDIO_OUTPUT_FLAG_FAST)

Test: make & run
Change-Id: I9cde640e6827b7aa6d62e9caade9e738227e299f