fix: implement optional dep for amqplib in mock package

[czy88840616]

remove amqplib package in @midwayjs/mock and add try cache block when other require it.

[gitpod-io]

[codecov-commenter]

Codecov Report

Merging #654 into 2.x will decrease coverage by 0.12%.
The diff coverage is 57.14%.

@@            Coverage Diff             @@
##              2.x     #654      +/-   ##
==========================================
- Coverage   84.15%   84.02%   -0.13%     
==========================================
  Files          96       96              
  Lines        3963     3976      +13     
  Branches      648      652       +4     
==========================================
+ Hits         3335     3341       +6     
- Misses        615      622       +7     
  Partials       13       13              

Impacted Files	Coverage Δ
packages/bootstrap/src/bootstrap.ts	70.31% <0.00%> (ø)
packages/decorator/src/common/constant.ts	100.00% <ø> (ø)
...ges/decorator/src/microservice/rabbitmqConsumer.ts	28.57% <ø> (ø)
packages/web/src/config/plugin.ts	100.00% <ø> (ø)
packages/mock/src/client/rabbitMQ.ts	9.23% <17.85%> (+0.76%)	⬆️
packages/decorator/src/web/response.ts	21.42% <50.00%> (-0.80%)	⬇️
packages/rabbitmq/src/mq.ts	45.45% <77.77%> (+0.74%)	⬆️
packages/core/src/context/container.ts	100.00% <100.00%> (ø)
packages/core/src/context/midwayContainer.ts	94.21% <100.00%> (ø)
packages/core/src/util/isClass.ts	100.00% <100.00%> (ø)
... and 5 more

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