Support line comment and block comment in PPL

[LantaoJin]

Description

Adding both block comment /* ... */ and line comment // support for PPL.
For example:

source=otel_logs /* Timestamped text record generated by OpenTelemetry framework */
| where kind = 'SPAN_KIND_CLIENT' // only calculate on client
| eval r = 0.99  /* precision */ | stats sum(droppedEventsCount * r) as lostEvents

Issues Resolved

Resolves #2805

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[dai-chen]

Thanks for the changes!

[LantaoJin]

Gently ping @penghuo @vamsi-amazon @YANG-DB

[opensearch-trigger-bot]

This PR is stalled because it has been open for 30 days with no activity.

[opensearch-trigger-bot]

This PR is stalled because it has been open for 30 days with no activity.

[YANG-DB]

hi @LantaoJin
if this PR is still relevant plz merge and resolve conflicts, if not can we close the PR ?
thanks

[LantaoJin]

Updated, gently ping @dai-chen @penghuo

[dai-chen]

I saw our SQL support line comment by # or --. This PPL line comment syntax is trying to consistent with SPL?

[LantaoJin]

This PPL line comment syntax is trying to consistent with SPL?

Yes.

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/sql/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/sql/backport-2.x
# Create a new branch
git switch --create backport/backport-2806-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 e0b72683a1ad4758276be802bfaf2c8de0e01d7d
# Push it to GitHub
git push --set-upstream origin backport/backport-2806-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/sql/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-2806-to-2.x.