Combined cloud blob crypto service

[lightningrob]

Combined changes from @dharju and @lightningrob.

[codecov-io]

Codecov Report

Merging #1154 into master will increase coverage by 0.09%.
The diff coverage is 93.95%.

@@             Coverage Diff              @@
##             master    #1154      +/-   ##
============================================
+ Coverage     69.59%   69.68%   +0.09%     
- Complexity     5244     5261      +17     
============================================
  Files           414      416       +2     
  Lines         32299    32438     +139     
  Branches       4113     4122       +9     
============================================
+ Hits          22478    22604     +126     
- Misses         8693     8709      +16     
+ Partials       1128     1125       -3

Impacted Files	Coverage Δ	Complexity Δ
...rc/main/java/com.github.ambry.cloud/VcrServer.java	77.41% <ø> (-0.94%)	4 <0> (ø)
...c/main/java/com.github.ambry.cloud/VcrMetrics.java	100% <100%> (ø)	2 <1> (+1)	⬆️
...main/java/com.github.ambry/config/CloudConfig.java	100% <100%> (ø)	1 <0> (ø)	⬇️
...ava/com.github.ambry.cloud/CloudBackupManager.java	83.78% <100%> (+0.45%)	3 <0> (ø)	⬇️
...java/com.github.ambry.cloud/CloudBlobMetadata.java	95% <100%> (+1.81%)	27 <7> (+6)	⬆️
...java/com.github.ambry.router/GCMCryptoService.java	89.87% <100%> (ø)	10 <0> (ø)	⬇️
...ithub.ambry.cloud/azure/AzureCloudDestination.java	81.01% <100%> (+0.36%)	19 <0> (ø)	⬇️
...ain/java/com.github.ambry/config/RouterConfig.java	100% <100%> (ø)	1 <0> (ø)	⬇️
...ithub.ambry.router/SingleKeyManagementService.java	89.47% <66.66%> (-4.65%)	6 <1> (+1)
...b.ambry.cloud/CloudBlobCryptoAgentFactoryImpl.java	81.81% <81.81%> (ø)	2 <2> (?)
... and 16 more

---

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 7ab285a...80b2163. Read the comment docs.

[zzmao]

Two comments on prod. Will look at test soon.

[zzmao]

LGTM.