Explain the changes

1. get user supplemental dynamically by calling getgrouplist. getgrouplist will scan the system for all groups that the user is a part of. that way will be able to set the users groups without specifying them in the account configuration. if specified, supplemental groups set by the account configuration will take precedence, and be set as the users groups. also in case no record of the user can be found in the os and no supplemental groups were defined in the account the supplemental groups list will be set as empty
2. some tests were using the uid 5, which is a system reserved uid, causing the feature to give them root group permissions. changed the uid and gid to ones not reserved by the OS
3. there was a suggestion to use getlogin_r to get the user name for getgrouplist. this function gets the name of the user logged to the terminal. this function uses the /var/run/utmp. in my implementation I used
   getpwuid instead which gets the user name by uid using the /etc/passwd file. I used it because its more flexible and according to documentation getlogin_r uses the /etc/passwd file anyways. also getlogin_r might not work because the uid was switched to be different then the one used to run the process(root)
4. added implementation and tests for mac-os. run the tests same as on linux. only run on macos environment

Issues:

Fixed #8712

Gaps

#8710 - list objects fail when using supplemental groups

continue #8552

Testing Instructions:

before running all tests on the code changes please run:
npm run build:native
manual tests (examples for linux):

1. create new group in the os:
   groupadd -g 1022 new_group
2. create new user in the os:
   useradd -c test_user2 -m test_user2 -p -u 1033 -g 1034
3. add user to the new group:
   usermod -a -G new_group test_user2
4. create new noobaa account with the new groups gid:
   sudo node src/cmd/manage_nsfs.js account add --name test_user1 --uid 1022 --gid 1022
5. create a second account with the new users gid and uid:
   sudo node src/cmd/manage_nsfs.js account add --name test_user1 --uid 1033 --gid 1034
6. create a new bucket using the forst user
   test_user1_s3api create-bucket --bucket test_bcuket
7. add bucket policy to allow putObject to test_user2
8. put new object to the new bucket using the second user test_user2:
   test_user2_s3api put-object --bucket test_bcuket --key key1 --body <path_to_body>
9. operation should succeed

automatic tests:
sudo node ./node_modules/mocha/bin/mocha src/test/unit_tests/test_nsfs_access.js

Note: building and testing was done on Linux and Mac machines

• Doc added/updated
• Tests added