Add two additional fly plan stubs - one that uses PCOMP, and one that uses a PULSE

[jwlodek]

It would be good to have built in plan stubs that allow for you to run flys using these two other methods.

### Tasks
- [ ] https://github.com/bluesky/ophyd-async/issues/375
- [ ] https://github.com/bluesky/ophyd-async/issues/376

[coretl]

This is to make:

• position triggered pulses
• time based pulses within a postion based gate