Add mobile operator observer for qpl logging.
Summary: Add mobile operator observer to measure performance of each operator run, the result will also log into QPL event: [MOBILE_OPERATOR_STATS ](https://fburl.com/quicklog/8773a00a).
Test Plan:
Run pytext model through BI cloaking flow on lite-interpreter and verify logs are sent:
1. buck install -r fb4a
2. Go to internal setting and find MobileConfig, search for android_bi_infra_cloaking_iab_models and set the following params:
a. sample_rate: 1.0
b. enabled: true
c. use_bytedoc_pytorch_model: true
d. use_bytedoc_caffe2_model: false
e. use_full_jit: false
3. Go back to new feed and scroll down until find an ads which will direct you to offsite webpage;
4. Click on the ads, wait for the offsite ads loads;
5. Click back to news feed;
6. Go to scuba table: https://fburl.com/scuba/er7t4g9u and see all the operator runs have been logged:
{F223250762}
Reviewed By: ljk53
Differential Revision: D18131224
fbshipit-source-id: 23e2f6e2a9851c04b29511b45dc53f3cce03e8a0
