Support singleton PostProcessor

[HzjNeverStop]

1. 支持通过 @SingletonSofaPostProcessor 注解指定 PostProcessor 以单例形式共享；
2. 优化一些 PostProcessor 实现，减少 byType 注入，避免触发 FactoryBean 提前初始化

[codecov]

Codecov Report

Merging #1029 (8eceb15) into master (5e153c8) will decrease coverage by 0.00%.
The diff coverage is 34.37%.

@@             Coverage Diff              @@
##             master    #1029      +/-   ##
============================================
- Coverage     11.37%   11.37%   -0.01%     
  Complexity       39       39              
============================================
  Files           312      312              
  Lines          9145     9182      +37     
  Branches       1259     1261       +2     
============================================
+ Hits           1040     1044       +4     
- Misses         7954     7986      +32     
- Partials        151      152       +1     

Impacted Files	Coverage Δ
...y/sofa/isle/loader/DynamicSpringContextLoader.java	0.00% <0.00%> (ø)
...a/runtime/proxy/ProxyBeanFactoryPostProcessor.java	0.00% <ø> (ø)
...ay/sofa/runtime/spring/JvmFilterPostProcessor.java	83.33% <ø> (ø)
...time/spring/SofaShareBeanFactoryPostProcessor.java	0.00% <0.00%> (ø)
...me/spring/share/SofaPostProcessorShareManager.java	0.00% <0.00%> (ø)
...onfigure/runtime/SofaRuntimeAutoConfiguration.java	91.17% <50.00%> (ø)
...spring/RuntimeContextBeanFactoryPostProcessor.java	76.00% <100.00%> (-19.00%)	⬇️
...untime/spring/ServiceBeanFactoryPostProcessor.java	28.33% <100.00%> (-0.65%)	⬇️
...ofa/runtime/spring/bean/SofaBeanNameGenerator.java	33.33% <0.00%> (-2.39%)	⬇️
... and 3 more

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[ujjboy]

LGTM