Add etcd lock

[stulzq]

What this PR does:

Add etcd lock

Which issue(s) this PR fixes:

Fixes #127

[mosn-community-bot]

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[seeflood]

写的很棒！！感谢贡献

[codecov-commenter]

Codecov Report

Merging #128 (1906c1d) into main (caf6a62) will increase coverage by 0.14%.
The diff coverage is n/a.

❗ Current head 1906c1d differs from pull request most recent head 0fcd80c. Consider uploading reports for the commit 0fcd80c to get more accurate results

@@            Coverage Diff             @@
##             main     #128      +/-   ##
==========================================
+ Coverage   44.63%   44.77%   +0.14%     
==========================================
  Files          41       41              
  Lines        1425     1425              
==========================================
+ Hits          636      638       +2     
+ Misses        741      740       -1     
+ Partials       48       47       -1     

Impacted Files	Coverage Δ
...kg/filter/network/tcpcopy/persistence/work_pool.go	90.00% <0.00%> (+5.00%)	⬆️

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[seeflood]

刚发现昨晚的cr忘提交了……

[seeflood]

LGTM

[seeflood]

Thanks again for your contribution,and welcome to the MOSN&Layotto community!