feat: add symbolic tstops support to ODESystem

[AayushSabharwal]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

Add any other context about the problem here.

[isaacsas]

This is really nice. Is there any reason not to add to SDE and jump systems too?

[AayushSabharwal]

I'm yet to add the solver infrastructure there

[ChrisRackauckas]

What's up with the homotopy continuation tests? That's clearly not related though, but should get a follow up.

[ChrisRackauckas]

This is really nice. Is there any reason not to add to SDE and jump systems too?

The solvers will need to integrate with it. Let's allow this to be tried out a bit, but the interface in theory can work on any algorithm that defines the trait, so we can roll it out to more if it's working well. There's a few things to figure out with component handling with this.

[AayushSabharwal]

What's up with the homotopy continuation tests? That's clearly not related though, but should get a follow up.

Weird that the only failure is on LTS. I'll investigate.