fix: add keep alive logic for xlinectl lock command

[Phoenix500526]

Closes: #664

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?) fix issue #664

• what changes does this pull request make?

  1. remove the lease client from LockClient
  2. add keep alive logic for xlinectl lock cmd

• are there any non-obvious implications of these changes? (does it break compatibility with previous versions, etc)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 16.66667% with 30 lines in your changes are missing coverage. Please review.

Project coverage is 75.22%. Comparing base (e35b35a) to head (138250e). Report is 28 commits behind head on master.

Files	Patch %	Lines
crates/xlinectl/src/command/lock.rs	0.00%	14 Missing :warning:
...xline-test-utils/src/bin/validation_lock_client.rs	0.00%	9 Missing :warning:
crates/xlinectl/src/command/lease/keep_alive.rs	0.00%	6 Missing :warning:
crates/xline-client/src/clients/lock.rs	83.33%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #666 +/- ## ========================================== - Coverage 75.55% 75.22% -0.34% ========================================== Files 180 182 +2 Lines 26938 26990 +52 Branches 26938 26990 +52 ========================================== - Hits 20353 20302 -51 - Misses 5366 5428 +62 - Partials 1219 1260 +41 ```

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[Phoenix500526]

Closed since it's duplicated with pr #820