Change dokka configs to being per-project

[williamito]

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

Fixes #1754

Description
Change dokka configs back to being per-project to fix external library links in generated documentation.

Alternative(s) considered
I saw that implementationguide had dokka added to it, but do we need generated docs for it?

Type
Choose one: Bug fix / documentation

Screenshots (if applicable)

Checklist

• I have read and acknowledged the Code of conduct.
• I have read the Contributing page.
• 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 demo app(s) to verify my change fixes the issue and/or does not break the demo app(s).

[codecov]

Codecov Report

Merging #1758 (5dea1a3) into master (9b1df44) will increase coverage by 41.82%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master    #1758       +/-   ##
=============================================
+ Coverage          0   41.82%   +41.82%     
- Complexity        0      386      +386     
=============================================
  Files             0      151      +151     
  Lines             0     5487     +5487     
  Branches          0      984      +984     
=============================================
+ Hits              0     2295     +2295     
- Misses            0     2833     +2833     
- Partials          0      359      +359     

Impacted Files	Coverage Δ
.../google/android/fhir/db/impl/dao/LocalChangeDao.kt	88.70% <0.00%> (ø)
...fhir/datacapture/enablement/EnablementEvaluator.kt	36.36% <0.00%> (ø)
.../google/android/fhir/index/entities/StringIndex.kt	100.00% <0.00%> (ø)
...QuestionnaireItemCheckBoxGroupViewHolderFactory.kt	0.00% <0.00%> (ø)
...main/java/com/google/android/fhir/DatastoreUtil.kt	0.00% <0.00%> (ø)
...load/HttpVerbBasedBundleEntryComponentGenerator.kt	0.00% <0.00%> (ø)
.../android/fhir/datacapture/QuestionnaireFragment.kt	58.55% <0.00%> (ø)
...r/datacapture/views/QuestionnaireItemHeaderView.kt	82.35% <0.00%> (ø)
...download/ResourceParamsBasedDownloadWorkManager.kt	0.00% <0.00%> (ø)
...google/android/fhir/datacapture/MoreExpressions.kt	0.00% <0.00%> (ø)
... and 141 more

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[jingtang10]

thanks @williamito