Send, sendto, recv, recvfrom syscall comments and tests

[davidge20]

Description

Commented send, sendto, recv, recvfrom syscalls.
Added basic tests to flag errors in send and ran exhaustive tests on unix sockets for sends/receives

Fixes # (issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Test A - `ut_lind_net_recvfrom_unix()
• Test B - 'ut_lind_net_send_close_server_socket_early()'
• Test C - 'ut_lind_net_send_no_peer_address()'

Checklist:

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been added to a pull request and/or merged in other modules (native-client, lind-glibc, lind-project)

[ve1nard]

one small question

[ve1nard]

lgtm

[yashaswi2000]

added some questions for clarification

[yashaswi2000]

LGTM

[rennergade]

@JustinCappos can you give David feedback so we can finalize this?