TelephonyStatsLib, support handling atoms and metrics

Introduces TelephonyStatsLib to help with atom collection.
 - Atoms-Classes : Two types of abstract classes are provided
   pushed atom and pulled atom.
 - Persist function : For the pulled atom, it provides save the data
   to a file in case of sudden data loss (such as a process dies).
 - Provides callbacks for pulled atoms such as continuous gauges.
 - Provides write (for pushed) and append (for pulled) api
 - Storage class stores atoms internally and persistantly
Add UnitTest
 - atest TelephonyStatsLibTests

Bug: 235436630
Test: atest StatsLibTests
Change-Id: I5b95a641dfa20b23e89059c59c3e95ae07aac42b
14 files changed
tree: 3147b4d742f4f683c40750c59fc2102ef3a1a16c
  1. apex/
  2. libs/
  3. services/
  4. .gitignore
  5. OWNERS
  6. PREUPLOAD.cfg
  7. TEST_MAPPING