feat: add exec command args for xlinectl lock command

[bhavik-goplani]

Please briefly answer these questions:

• what problem are you trying to solve? (or if there's no problem, what's the motivation for this change?) https://github.com/xline-kv/Xline/issues/823

• what changes does this pull request make? Added exec command support to xlinectl lock command. Updated the README with new examples for lock.

• are there any non-obvious implications of these changes? (does it break compatibility with previous versions, etc) No

Additional comments: I'm not sure how to test the exec command args. I thought of two solutions:

1. Extend LockRequest or Test Case Representation: Add a way to represent the exec commands that should be executed after the lock is acquired. This could be a new field in the LockRequest struct or a separate structure linked to the test case.
2. Modify the Test Case: Adjust the test case in macros.rs to include the exec commands as part of the expected outcome.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 36.36364% with 14 lines in your changes missing coverage. Please review.

Project coverage is 75.61%. Comparing base (e35b35a) to head (038bca5). Report is 108 commits behind head on master.

Files	Patch %	Lines
crates/xlinectl/src/command/lock.rs	36.36%	14 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #846 +/- ## ========================================== + Coverage 75.55% 75.61% +0.05% ========================================== Files 180 187 +7 Lines 26938 27685 +747 Branches 26938 27685 +747 ========================================== + Hits 20353 20933 +580 - Misses 5366 5465 +99 - Partials 1219 1287 +68 ```

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[CrystalAnalyst]

Sorry for the late response. I really appreciate your interest about Xline and the contribution you've made. I've reviewd your code logic, it's natural and clear. However, recently we did a major change about this xlinectl lock command, you can refer to the #820. In essence, the lock usage is changed from : client.lock_client().lock(req).await?; to : let mut xutex = Xutex::new().await?; let xutex_guard = xutex.lock_unsafe().await? So you may update your repo and make corresponding change, especially the : pub(crate) async fn execute(client: &mut Client, matches: &ArgMatches) -> Result<()>. And for the test, we have a validation test in the: Xline/scripts/validation_test.sh, you can add your test case here. If you have any questions, feel free to ask.

[bhavik-goplani]

@CrystalAnalyst Thanks for the feedback. I'll close this pull request and create a new PR after pulling the recent changes.