Implementations:
1. local check of subject.CN
2. check run in external process
3. check delegated to REST-API

Test Cases:
1. Test inventory invocation
2. Test local inventory
3. Test external inventory

Test Configurations:
1. Enrollment with local inventory path
2. Enrollment with plugin path for external inventory checker process

- InventoryPluginBase class for common structures and methods
- Use plain JSON structure for certificate request information
- Use environment variable RA_INVENTORY_EXEC to pass on path to external
  checker to lightweightCmpRa
- Test case uses scripts/external-inventory-example.pyw as external
  checker

- Change from apache http client to java.net.http
- Use plain JSON structure for certificate request information
- Adjust test case to use environment variable RA_INVENTORY_URL for HTTP
  service

…ies: checks request against rule-set from RA_DSL_RULE file

…ker container

…lication