Upload local changed resources using Bundle transaction

[aditya-07]

IMPORTANT: All PRs must be linked to an issue (except for extremely trivial and straightforward changes).

Fixes #1021

Description
Instead of making individual CRUD request for each local change, we would Bundle multiple resources inside a Bundle Transaction.
This PR also mandates for now that all the resources are created on server using Http PUT instead of POST.

Alternative(s) considered
Have you considered any alternatives? And if so, why have you chosen the approach in this PR?

Type
Choose one: Feature

Screenshots (if applicable)

Checklist

• I have read and acknowledged the Code of conduct
• I have read How to Contribute
• I have read the Developer's guide
• I have signed the Google Individual CLA, or I am covered by my company's Corporate CLA
• I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach
• I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the style guide of this project
• I have run ./gradlew check and ./gradlew connectedCheck to test my changes locally
• I have built and run the reference app(s) to verify my change fixes the issue and/or does not break the reference app(s)

[codecov]

Codecov Report

Merging #1084 (a99bfd9) into master (27cfe1f) will decrease coverage by 0.04%.
The diff coverage is 68.46%.

@@             Coverage Diff              @@
##             master    #1084      +/-   ##
============================================
- Coverage     84.57%   84.53%   -0.05%     
- Complexity      632      646      +14     
============================================
  Files           135      140       +5     
  Lines         10407    10488      +81     
  Branches        787      795       +8     
============================================
+ Hits           8802     8866      +64     
- Misses         1209     1223      +14     
- Partials        396      399       +3     

Impacted Files	Coverage Δ
...ava/com/google/android/fhir/impl/FhirEngineImpl.kt	42.00% <24.13%> (-31.34%)	⬇️
...oid/fhir/sync/bundle/TransactionBundleGenerator.kt	77.27% <77.27%> (ø)
.../google/android/fhir/sync/bundle/BundleUploader.kt	77.77% <77.77%> (ø)
...a/com/google/android/fhir/sync/FhirSynchronizer.kt	81.57% <80.00%> (+14.54%)	⬆️
...ndle/HttpVerbBasedBundleEntryComponentGenerator.kt	90.90% <90.90%> (ø)
...android/fhir/db/impl/entities/LocalChangeEntity.kt	100.00% <100.00%> (ø)
...main/java/com/google/android/fhir/sync/Uploader.kt	100.00% <100.00%> (ø)
...ttpVerbBasedBundleEntryComponentImplementations.kt	100.00% <100.00%> (ø)

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[jingtang10]

like the abstraction of the generator much better - thanks @aditya-07 🙏