feat: support gateway context, feign eager-load support default value.

[fuyuwei01]

PR Type

Describe what this PR does for and how you did.

Adding the issue link (#xxx) if possible.

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.

[codecov]

Codecov Report

Attention: Patch coverage is 9.35065% with 349 lines in your changes missing coverage. Please review.

Project coverage is 60.06%. Comparing base (b577b54) to head (47c638e).
Report is 1 commits behind head on hoxton.

Files with missing lines	Patch %	Lines
...d/plugin/gateway/context/ContextGatewayFilter.java	0.00%	85 Missing ⚠️
...teway/context/ContextGatewayPropertiesManager.java	0.00%	64 Missing ⚠️
...ent/cloud/plugin/gateway/context/GroupContext.java	0.00%	62 Missing ⚠️
...instrument/feign/FeignEagerLoadSmartLifecycle.java	0.00%	25 Missing and 1 partial ⚠️
...ugin/gateway/context/ContextGatewayProperties.java	0.00%	14 Missing ⚠️
...plugin/gateway/GatewayPluginAutoConfiguration.java	0.00%	13 Missing ⚠️
.../gateway/context/ContextRoutePredicateFactory.java	0.00%	12 Missing ⚠️
...n/gateway/context/GatewayConfigChangeListener.java	0.00%	12 Missing ⚠️
...tiveLoadBalancerClientFilterBeanPostProcessor.java	0.00%	9 Missing ⚠️
...n/gateway/context/ContextGatewayFilterFactory.java	0.00%	9 Missing ⚠️
... and 13 more

Additional details and impacted files

@@             Coverage Diff              @@
##             hoxton    #1545      +/-   ##
============================================
- Coverage     62.92%   60.06%   -2.86%     
  Complexity       22       22              
============================================
  Files           360      366       +6     
  Lines          8350     8574     +224     
  Branches       1029     1051      +22     
============================================
- Hits           5254     5150     -104     
- Misses         2627     2961     +334     
+ Partials        469      463       -6     

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[SkyeBeFreeman]

LGTM.