refactor: replace ANTLR parser with omni recursive descent parser

[h3n4l]

Summary

• Replace bytebase/parser/mongodb (ANTLR-based) with bytebase/omni/mongo (hand-written recursive descent parser)
• Rewrite translator from ANTLR visitor pattern to direct AST type switches, reducing ~3400 lines to ~1600 lines
• Remove antlr4-go/antlr/v4 runtime dependency and its replace directive

Test plan

• go build ./... passes
• golangci-lint run passes with 0 issues
• All existing integration tests pass across MongoDB 4.4, 8.0, and DocumentDB

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR refactors MongoDB shell parsing/translation by replacing the previous ANTLR-based parser/visitor implementation with the github.com/bytebase/omni/mongo recursive-descent parser and a new translation layer built on omni AST node type switches.

Changes:

• Replace ANTLR parse-tree visitor workflow with omni parsing (mongo.Parse) and direct AST translation (translateNode).
• Rework value/helper decoding to consume omni AST nodes for BSON conversion (documents, arrays, literals, helper calls).
• Update module dependencies to drop ANTLR/runtime and introduce github.com/bytebase/omni.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
internal/translator/visitor.go	Removes the ANTLR visitor-based operation extraction implementation.
internal/translator/translator.go	Switches parsing entrypoint to mongo.Parse and routes to omni AST translation.
internal/translator/translate.go	Adds omni AST → Operation translation via type switches and method dispatch.
internal/translator/helpers.go	Replaces parse-context value conversion with omni AST node conversion helpers.
internal/translator/database.go	Ports DB-level argument extraction to omni AST args.
internal/translator/collection.go	Ports collection/cursor method arg parsing and option extraction to omni AST args.
internal/translator/bson_helpers.go	Ports helper function decoding to omni AST helper calls.
go.mod	Removes ANTLR/parser deps; adds github.com/bytebase/omni and bumps/adjusts related deps.
go.sum	Updates checksums to reflect dependency graph changes.

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