Added grammar files in sql and spark repo, changed workflow to publish zip file containing all .g4 files to maven under /opensearch-language-grammar

[ahkcs]

This PR adds a GitHub Actions workflow that automatically packages and publishes ANTLR grammar files (.g4) from the unified-grammar/src/main/antlr4 directory to the Maven snapshot repository.

Implementation Details

The workflow:

Packages all ANTLR .g4 grammar files into a single ZIP file
Creates the necessary directory structure in the Maven repository
Publishes the ZIP to https://aws.oss.sonatype.org/content/repositories/snapshots/org/opensearch/opensearch-language-grammar-poc
Generates appropriate Maven metadata including POM files and checksum files
Tags the published artifacts with the source commit ID for traceability
Purpose

This allows grammar files to be versioned and distributed separately from the main codebase, enabling:

Grammar reuse across different projects
Independent versioning of grammar definitions
Easier integration of our grammar definitions in third-party tools
Technical Notes

The workflow runs on push to main branch and can also be triggered manually
Uses AWS Secrets Manager to securely retrieve Maven repository credentials
Creates a version 1.0.0-SNAPSHOT by default (configurable in the workflow)
Requires the AWS IAM role specified in PUBLISH_SNAPSHOTS_ROLE secret
Testing

The workflow was tested by manually triggering it and verifying the artifacts were correctly published to the Maven repository at the specified path.

[noCharger]

why do we need to add the g4?

[ahkcs]

why do we need to add the g4?

In the workflow we're creating, we're packaging and publishing the .g4 files that already exist in the repository at unified-grammar/src/main/antlr4. The workflow depends on those files being present in the repository.

[noCharger]

we're packaging and publishing the .g4 files that already exist in the repository at unified-grammar/src/main/antlr4. The workflow depends on those files being present in the repository.

let's rename the dir