Combines searchGroupingMembers and getGroupingMembers endpoints

[JorWo]

Ticket Link

GROUPINGS-1863

List of squashed commits

• Moves numberOfGroupingMembers from GroupingsService to GroupingOwnerService
• Fixes PascalCase use of SearchString into camelCase (searchString)
• Fixes GroupingsRestControllerv2_1.updateOptAttribute in Swagger to use correct id

Test Checklist

• Exhibits Clear Code Structure:
• Project Unit Tests Passed:
• Project Integration Tests Passed:
• Executes Expected Functionality:
• Tested For Incorrect/Unexpected Inputs:

[JorWo]

The @Cacheable and @CacheEvict annotations uses Spring Boot's cache to simulate pagination. This allowed me to combine the two endpoints and simplify code in the React UI. Since GrouperClient does not have pagination support when searching for members in a group by a searchString, caching the result was the next best solution. Once an add/remove/reset happens to a groupPath, the cache evicts for the groupPath so the data returned is always correct.

I will wait for #624 to be completed before merging this.