feat:refactor SDKContext as static.

[SkyeBeFreeman]

PR Type

Refactoring (no functional changes, no api changes).

Describe what this PR does for and how you did.

Adding the issue link (#xxx) if possible.

fixes #982
fixes #984

Note

Checklist

• Add information of this PR to CHANGELOG.md in root of project.
• Add documentation in javadoc or comment below the PR if necessary.

Checklist (Optional)

• Will pull request to branch of 2020.0.
• Will pull request to branch of 2022.0.

[codecov]

Codecov Report

Merging #995 (f49c7c1) into 2022.0 (841a39a) will increase coverage by 0.05%.
The diff coverage is 91.60%.

@@             Coverage Diff              @@
##             2022.0     #995      +/-   ##
============================================
+ Coverage     82.89%   82.95%   +0.05%     
- Complexity     1583     1599      +16     
============================================
  Files           238      239       +1     
  Lines          5244     5320      +76     
  Branches        610      618       +8     
============================================
+ Hits           4347     4413      +66     
- Misses          540      549       +9     
- Partials        357      358       +1     

Impacted Files	Coverage Δ
...cloud/polaris/registry/PolarisServiceRegistry.java	71.42% <76.47%> (-0.14%)	⬇️
...loud/polaris/context/PolarisSDKContextManager.java	90.14% <90.14%> (ø)
...config/PolarisCircuitBreakerAutoConfiguration.java	100.00% <100.00%> (ø)
...eactivePolarisCircuitBreakerAutoConfiguration.java	100.00% <100.00%> (ø)
...onfig/PolarisConfigBootstrapAutoConfiguration.java	85.71% <100.00%> (ø)
.../polaris/DiscoveryPropertiesAutoConfiguration.java	100.00% <100.00%> (ø)
...oud/polaris/discovery/PolarisDiscoveryHandler.java	100.00% <100.00%> (+17.39%)	⬆️
...h/PolarisRefreshApplicationReadyEventListener.java	76.19% <100.00%> (ø)
...discovery/refresh/PolarisRefreshConfiguration.java	100.00% <100.00%> (ø)
...lancer/PolarisLoadBalancerClientConfiguration.java	89.47% <100.00%> (ø)
... and 7 more

... and 3 files with indirect coverage changes

[ShanyouYu-Sean]

LGTM

[ShanyouYu-Sean]

LGTM

[ShanyouYu-Sean]

LGTM