Add URL parameter to the Web UI to provide one click link for validation

[emmambd]

Describe the problem

For companies who validate many GTFS feeds at once, they want a convenient one click link for running the validator, rather than having to type it into the form and press submit.

Proposed solution

Include a URL parameter in the validator:

Pattern: https://gtfs-validator.mobilitydata.org/?url={encoded url}
Example: https://gtfs-validator.mobilitydata.org/?url=https%3A%2F%2Fpassio3.com%2Fharrisonburg%2FpassioTransit%2Fgtfs%2Fgoogle_transit.zip

Alternatives you've considered

No response

Additional context

No response