Improve LTE signal bar level with flexible RSRQ and RSSNR threshold

Current AOSP LTE signal bar has following limitation:
- For Threshold type, "RSRP & RSSNR" or "RSRP only" are selectable,
  but "RSRP & RSRQ" is unavailable.
- For threshold value, RSRP is flexible by carrier config,
  but RSSNR is hard-coded.
- The signal strength reporting criteria apply to only the RSRP.

This change allows following customizations by new carrier config:
- Threshold type can select "RSRP & RSRQ" too.
- Threshold value of RSRQ and RSSNR can be flexible.
- RSRQ and RSSNR thresholds can set signal strength reporting criteria.

Test: auto - Confirmed that run
FrameworksTelephonyTests#testSignalStrength and it has no problem.
Test: auto - Confirmed that run
FrameworksTelephonyTests#SignalThresholdInfoTest and it has no problem.
Bug: 133400544

Change-Id: I37d0dc5ff41169b0309cfaabaa0f2595894b3749
Merged-In: I37d0dc5ff41169b0309cfaabaa0f2595894b3749