Add Integration tests for Operation Policy Import/Export APIs

[BLasan]

Purpose Fixes: wso2/api-manager#223 wso2/api-manager#489

Approach Implemented the following test cases.

• testCommonOperationPolicyExport
• testInvalidCommonOperationPolicyExport
• testImportNewCommonOperationPolicy
• testImportExistingCommonOperationPolicy
• testImportInvalidCommonOperationPolicy
• testCommonOperationPolicyExportWithJSONContent

[codecov[bot]]

Codecov Report

Merging #12938 (31e9268) into master (adc0375) will increase coverage by 7.12%. The diff coverage is 75.00%.

:exclamation: Current head 31e9268 differs from pull request most recent head dae59b6. Consider uploading reports for the commit dae59b6 to get more accurate results

@@             Coverage Diff              @@
##             master   #12938      +/-   ##
============================================
+ Coverage     15.53%   22.65%   +7.12%     
- Complexity      731     1087     +356     
============================================
  Files           242      241       -1     
  Lines         10757    10729      -28     
  Branches       1120     1117       -3     
============================================
+ Hits           1671     2431     +760     
+ Misses         9049     8254     -795     
- Partials         37       44       +7     

Flag	Coverage Δ
integration_tests	22.65% <75.00%> (+7.12%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...clients/publisher/api/v1/OperationPoliciesApi.java	88.88% <ø> (+60.31%)	:arrow_up:
...s/publisher/api/v1/dto/OperationPolicyDataDTO.java	44.54% <75.00%> (+44.54%)	:arrow_up:
...1/dto/AdditionalSubscriptionInfoSolaceURLsDTO.java	0.00% <0.00%> (-30.00%)	:arrow_down:
...SubscriptionInfoSolaceDeployedEnvironmentsDTO.java	0.00% <0.00%> (-27.78%)	:arrow_down:
...syncAPISpecificationValidationResponseInfoDTO.java	33.72% <0.00%> (-9.31%)	:arrow_down:
...to/AsyncAPISpecificationValidationResponseDTO.java	26.08% <0.00%> (-6.53%)	:arrow_down:
...utils/publisher/rest/client/model/Environment.java	56.04% <0.00%> (-3.30%)	:arrow_down:
...on/clients/internal/api/dto/ThrottledEventDTO.java
.../publisher/api/v1/dto/APICorsConfigurationDTO.java	40.74% <0.00%> (+1.85%)	:arrow_up:
...s/admin/api/dto/SubscriptionThrottlePolicyDTO.java	44.66% <0.00%> (+1.94%)	:arrow_up:
... and 63 more

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[wasuradananjith]

All the Git Actions are passed [1]. Hence, we can merge this PR.

[1] https://github.com/wso2/product-apim/actions/runs/2911311062