client: support create with context

[disksing]

Signed-off-by: disksing [email protected]

What problem does this PR solve?

Fix #1983

What is changed and how it works?

add NewClientWithContext

Check List

Tests

• Unit test

Related changes

• Need to cherry-pick to the release branch
• Need to be included in the release notes

[codecov-io]

Codecov Report

Merging #1993 into master will increase coverage by <.01%.
The diff coverage is 90%.

@@            Coverage Diff             @@
##           master    #1993      +/-   ##
==========================================
+ Coverage   77.41%   77.42%   +<.01%     
==========================================
  Files         178      178              
  Lines       18142    18149       +7     
==========================================
+ Hits        14045    14051       +6     
+ Misses       3014     3013       -1     
- Partials     1083     1085       +2

Impacted Files	Coverage Δ
client/client.go	72.1% <90%> (+2.08%)	⬆️
pkg/testutil/operator_check.go	88.88% <0%> (-11.12%)	⬇️
server/kv/etcd_kv.go	75.32% <0%> (-6.5%)	⬇️
server/heartbeat_streams.go	69% <0%> (-6%)	⬇️
server/member/leader.go	75.51% <0%> (-5.62%)	⬇️
pkg/etcdutil/etcdutil.go	88.4% <0%> (-2.9%)	⬇️
server/schedule/operator_controller.go	83.75% <0%> (+0.18%)	⬆️
pkg/btree/btree.go	87.65% <0%> (+0.8%)	⬆️
server/grpc_service.go	58.96% <0%> (+0.86%)	⬆️
server/config/option.go	91.24% <0%> (+0.92%)	⬆️
... and 5 more

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[rleungx]

/merge

[sre-bot]

/run-all-tests

[sre-bot]

cherry pick to release-3.0 failed

[sre-bot]

cherry pick to release-3.1 failed