i_1061 Prompt for credentials for pc2submit if none found

[johnbrvc]

Description of what the PR does

Add optional code (controlled by environment variable SUBMITCREDENTIALS == 'yes') to prompt the user for their contest credentials and add them to their ~/.netrc file. Added appropriate code ask for and confirm the user's credentials.
CI: Code cleanup - create constants for environment variables (there were already several environment variables hard-coded).
CI: Add -t # (--team_id #) to allow specification of the team_id to submit on behalf of
CI: Add environment variable SUBMITOMITEXTRAHELP=='yes' to not include help for the -c, -a, -u and -t options as these are typically not used by most users.

Issue which the PR addresses

Fixes #1061

Environment in which the PR was developed (OS,IDE, Java version, etc.)

Windows 11
java version "1.8.0_321"
Java(TM) SE Runtime Environment (build 1.8.0_321-b07)
Java HotSpot(TM) 64-Bit Server VM (build 25.321-b07, mixed mode)

Precise steps for testing the PR (i.e., how to demonstrate that it works correctly)

1. Remove any "localhost" entry in ~/.netrc
2. Start a contest (like sumithello)
3. Start a feeder and start it feeding 2023-06 API
4. Set/Unset the SUBMITCREDENTIALS environment to yes or no (to test various combinations)
5. Make a submission using pc2submit, eg. pc2submit -p a -y --team_id 1 samps/src/hello.cpp
6. You should be prompted to enter credentials if SUBMITCREDENTIALS was set to 'yes', otherwise it should just fail with a network exception of some sort.
7. You can repeat the test using different values of SUBMITCREDENTIALS, user and password, eg. team1/team1, administrator1/administrator1, or wrong credentials. Be sure to remove the entry for localhost from the ~/.netrc if you want to clear out the credentials for a new test.

[SamanwaySadhu]

#1063 also mentions that it fixes #1061. Maybe one of the two should mention Partial fix. Other than that it looks good.