Adding in remove capability for group members + csv download

[kiram15]

Jira ticket

Testing plan

• Navigate to a group detail page like https://localhost.stage.edx.org:1991/exec-ed-2u-integration-qa/admin/people-management/89e6451c-b187-44b2-b546-ad4511fc34ea
• Download full csv with no filters, ensure count from data table matches
• Search on a string, redownload, and ensure only expected rows show up
• Remove member with kabob menu

For all changes

• Ensure adequate tests are in place (or reviewed existing tests cover changes)

Only if submitting a visual change

• Ensure to attach screenshots
• Ensure to have UX team confirm screenshots

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 18 lines in your changes missing coverage. Please review.

Project coverage is 85.71%. Comparing base (a13b2a7) to head (9876b29).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...leManagement/GroupDetailPage/RemoveMemberModal.jsx	33.33%	10 Missing ⚠️
.../data/hooks/useEnterpriseGroupLearnersTableData.js	33.33%	4 Missing ⚠️
...nagement/GroupDetailPage/DownloadCsvIconButton.jsx	90.90%	2 Missing ⚠️
src/components/PeopleManagement/constants.js	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1367      +/-   ##
==========================================
- Coverage   85.79%   85.71%   -0.09%     
==========================================
  Files         623      625       +2     
  Lines       13589    13638      +49     
  Branches     2851     2848       -3     
==========================================
+ Hits        11659    11690      +31     
- Misses       1860     1878      +18     
  Partials       70       70              

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