fix: add modelgen support for granular read ops

[AaronZyLee]

Description of changes

Added granular modelgen support for Java
For the other libraries, the generated code has no problem and only library support is needed

• Android: fix: add granular read ops enum amplify-android#2265
• Swift: fix: add granular read ops enum amplify-swift#2720
• Flutter: feat(core): add granular model read operations amplify-flutter#2611
• Doc: chore: add callout for granular read use case docs#5084

Issue #, if available

aws-amplify/amplify-flutter#2526

Description of how you validated changes

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• Breaking changes to existing customers are released behind a feature flag or major version update
• Changes are tested using sample applications for all relevant platforms (iOS/android/flutter/Javascript) that use the feature added/modified

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Merging #537 (a54ddaa) into main (c6c7b7a) will not change coverage.
The diff coverage is n/a.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@           Coverage Diff           @@
##             main     #537   +/-   ##
=======================================
  Coverage   85.69%   85.69%           
=======================================
  Files         148      148           
  Lines        7380     7380           
  Branches     1962     1962           
=======================================
  Hits         6324     6324           
  Misses        959      959           
  Partials       97       97           

Impacted Files	Coverage Δ
...delgen-plugin/src/visitors/appsync-java-visitor.ts	94.80% <ø> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[phani-srikar]

Are we changing the behavior for only appsync-java-visitor or all other visitors as well? I assume this generateAuthRules method is common to all visitors? If that's the case, can we move this to a common visitor? Thanks

[AaronZyLee]

This is for java visitor only. It maps the input operation to the library-defined enum value. If not added here, the code in java will be generated as empty string.
For the other code generators, these ops will be simply parsed and generated in the final code and do not need additional mapping. You can see this in the snapshot changes for other visitors

[AaronZyLee]

• Swift: https://github.com/aws-amplify/amplify-codegen/pull/537/files#diff-b728b3bfd6e02d0683386efa2a8a74b95cc6f624d5f450db27764fe7edfac671R53-R55
• JS: https://github.com/aws-amplify/amplify-codegen/pull/537/files#diff-cc6588d1d5a98c0aba946398191679c0e2c1dbc8cc27d0c8b61e1a6d10cf34eeR2781-R2797
• Flutter: https://github.com/aws-amplify/amplify-codegen/pull/537/files#diff-38d85adcb8cc38618dae4676dc8ef3ae8c13ecf2fc73bbb00ce96519e7cbe2c6R3109-R3115