WIP: deploy pixiu as dubbo service egress gateway in k8s istio

[ma642]

What this PR does:

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-commenter]

Codecov Report

Merging #446 (5e2e29e) into develop (287bbeb) will decrease coverage by 0.23%. The diff coverage is 1.65%.

@@             Coverage Diff             @@
##           develop     #446      +/-   ##
===========================================
- Coverage    54.92%   54.69%   -0.24%     
===========================================
  Files          662      663       +1     
  Lines        77433    77702     +269     
===========================================
- Hits         42530    42498      -32     
- Misses       31278    31579     +301     
  Partials      3625     3625              

Impacted Files	Coverage Δ
...registry/zookeeper/application_service_listener.go	0.00% <ø> (ø)
pixiu/pkg/config/xds/apiclient/apiclient.go	0.00% <0.00%> (ø)
pixiu/pkg/config/xds/apiclient/grpc_envoy.go	0.00% <0.00%> (ø)
pixiu/pkg/config/xds/cds.go	52.89% <ø> (ø)
pixiu/pkg/config/xds/lds.go	58.03% <ø> (ø)
pixiu/pkg/config/xds/apiclient/grpc.go	17.85% <3.33%> (-0.10%)	:arrow_down:
pixiu/pkg/config/xds/xds.go	12.30% <7.40%> (-7.70%)	:arrow_down:
pixiu/pkg/server/dynamic_resource_manager.go	89.18% <100.00%> (ø)
pkg/istio-agent/xds_proxy_delta.go	45.07% <0.00%> (-8.30%)	:arrow_down:
pkg/kube/inject/watcher.go	48.14% <0.00%> (-6.18%)	:arrow_down:
... and 12 more

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[AlexStocks]

pls fix the file confliction.thx.

[PhilYue]

is the Sidecar start need special handling? the relevant code : sidecar.go