[OPE] Pass RuntimeOptions to the worker process

[VivekPanyam]

This PR passes user-specified RuntimeOptions to the OPE worker process when loading a model.

This enables us to easily add options without having to write special logic for OPE.

See #361 and #364 for examples.

[codecov]

Codecov Report

Merging #363 into master will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #363      +/-   ##
==========================================
+ Coverage   89.41%   89.44%   +0.03%     
==========================================
  Files          57       57              
  Lines        3900     3913      +13     
==========================================
+ Hits         3487     3500      +13     
  Misses        413      413              

Impacted Files	Coverage Δ
source/neuropod/multiprocess/multiprocess.cc	78.75% <100.00%> (+0.91%)	⬆️
...ource/neuropod/multiprocess/multiprocess_worker.cc	95.45% <100.00%> (+0.27%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e2afeab...44b8ab0. Read the comment docs.