Flex: Fix Continuous Pickup/Drop-Off Validation

[binh-dam-ibigroup]

Checklist

• Appropriate branch selected => this is against dev-flex
• Any modified or new methods or classes have helpful JavaDoc and code is thoroughly commented
• The description lists all applicable issues this PR seeks to resolve
• [na] The description lists any configuration setting(s) that differ from the default settings
• All tests and CI builds passing

Description

This PR includes the considering of permitted values for continuous pickup/drop-off validation.

To test in DT, replace the gtfs-lib commit number in pom.xml, for instance:

        <dependency>
            <groupId>com.github.ibi-group</groupId>
            <artifactId>gtfs-lib</artifactId>
            <version>fcf049ffd8cfcea1525998a301ebf77db5c62e4f</version>
            ...
        </dependency>

[josh-willis-arcadis]

LGTM