[Filters] Filters without the "possibleValues" and string values are causing errors

[jvigliotta]

Summary

When utilizing filters (https://github.com/nasa/openmct/tree/master/src/plugins/filters) without a possibleValues key (to be able to accept string values), an error is thrown here: https://github.com/nasa/openmct/blob/master/src/plugins/telemetryTable/components/table-footer-indicator.vue#L161 this is because comparator in this instance is a string.

There is also a case where the filters object for any properties that are set up to be strings (because the possibleValues is removed) are coming back to the telemetry providers as empty objects and not strings.

Expected vs Current Behavior

We need to handle string values in some manner.

Steps to Reproduce

1. set up a telemetry provider with filters (https://github.com/nasa/openmct/blob/master/src/plugins/filters/README.md)
2. remove the possibleValues property
3. add the telemetry endpoint you added filters for to a table
4. go into edit mode and scroll down to the filters "Global Filters" section and add in a string value
5. observe the error in console

Impact Check List

• Data loss or misrepresented data?
• Regression? Did this used to work or has it always been broken?
• Is there a workaround available?
• Does this impact a critical component?
• Is this just a visual bug with no functional impact?
• Does this block the execution of e2e tests?
• Does this have an impact on Performance?

[jvigliotta]

Testing

• visit an endpoint with string input filters enabled
• add string filters ("global" or view or both)
• make sure you can add them and edit them and that they persist
• in tables they should show in the footer for the value you entered
• in telemetry providers they should be in the options object in the arguments

[ozyx]

Verified fixed Testathon 11/16/23 -- tested locally with Event filters and works great