Fix Errno2 on GTFS RT validation

[erikamov]

Description

@ohrite and I refactored the code on gtfs_rt_parser.py using the tests created on the previous PR to then fix the issue #2780 to properly skip duplicate extracts instead of generating the error.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation

How has this been tested?

Tested locally:

❯ poetry run pytest --gcs
================================================ test session starts ================================================
platform darwin -- Python 3.9.19, pytest-8.3.3, pluggy-1.5.0
rootdir: /Users/erikaypacheco/Documents/workspace/data-infra/jobs/gtfs-rt-parser-v2
configfile: pyproject.toml
plugins: env-1.1.5
collected 10 items

tests/test_gtfs_rt_parser.py ..........                                                                       [100%]

================================================= warnings summary ==================================================
...
========================================= 10 passed, 111 warnings in 44.72s =========================================

Post-merge follow-ups

• No action required
• Actions required (specified below)

Check after the merge if the results on cal-itp-data-infra.staging.int_gtfs_quality__rt_validation_outcomes for next days/hours does not contain the Errno 2 reported on the issue.

[ohrite]

This PR lands two changes:

1. A GTFS-RT validator wrapper that has been factored into classes
2. A new logic change: duplicate (MD5) VP/TU/SA messages are marked as successful but will not load a result into BigQuery

[evansiroky]

Deferring review to @ohrite and @erikamov as they paired together.

[ohrite]

🍐 w/ @erikamov