Adds integration tests for code generator

[desaikd]

Issue #88:

Description of changes:

This PR works on adding pre-defined code gen test projects and roundtrip tests for the generated code.

List of changes:

• Renames beta-subcommand feature to experimental-code-gen (This makes it consistent with ion-rs on naming experimental feature. Also, since this feature is only used for code gen, using beta wouldn't be specific)
• Changes in struct and class template to sort field based on field name to generate consistent constructor signature for generated code.
• Adds code-gen-projects that has some pre-defined code generation projects for both Java(gradle project code-gen-demo) and Rust(cargo crate code-gene-demo).
  • Adds input Ion files for testing (/code-gen-proejcts/input)
  • Adds schema files for testing (/code-gen-proejcts/schema)
  • Adds cargo crate in rust/code-gen-demo for testing in Rust
  • Adds gradle project in java/code-gen-demo for testing in Java
  • Adds build process in both Rust and java projects, to generate code while building and use it for tetsing
  • Adds tests in both Rust and Java projects
• Adds code-gen-tests in ion-cli to invoke both Rust and Java projects for testing -Modifies CI workflow
  • Workflow modified to run code gen tests separately
  • Currently code gen tests only runs for ubuntu (Since code generation tests takes longer to clean previously generated code, generate code and then test for both Java and Rust, changed it to be just ubuntu. Also, seeing error in running gradle project in GitHub Actions for windows platform returns error which needs to be investigated: https://github.com/desaikd/ion-cli/actions/runs/8574599832/job/23501774774)
• Adds changes to sort schema file paths to preserve anonymous type names

Sample of running tests on ion-cli for code generator:

   Running tests/code-gen-tests.rs 

running 2 tests
     Removed X files, YMiB total
Starting a Gradle Daemon (subsequent builds will be faster)
> Task :clean

> Task :ionCodegen
Started generating code...
Code generation complete successfully!
Path to generated code: ion-cli/code-gen-projects/java/code-gen-demo/build/generated/java

> Task :compileJava
> Task :processResources NO-SOURCE
> Task :classes
> Task :compileTestJava
> Task :processTestResources NO-SOURCE
> Task :testClasses
> Task :test

BUILD SUCCESSFUL in Zs
5 actionable tasks: 5 executed
test roundtrip_tests_for_generated_code_gradle ... ok

running 3 tests
test tests::it_works ... ok
test tests::test_roundtrip_generated_code_structs_with_fields ... ok
test tests::test_roundtrip_generated_code_nested_structs ... ok

test result: ok. 3 passed; 0 failed; 0 ignored; 0 
....
test roundtrip_tests_for_generated_code_cargo ... ok

test result: ok. 2 passed; 0 failed; 0 ignored; 0 

Tests

• Adds code-gen-tests in ion-cli to invoke both Rust and Java
• Adds tests in code-gen-projects for both Rust and Java projects

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