ENH: Addition of Time Delay Parachute Deployment

[AidanPowers]

Is your feature request related to a problem? Please describe.

I am simulating a Loc-IV kit powered off of a Aerotech 38mm HP SU DMS Motor - H100W-14A

This kit has no avionics, and instead uses a fixed time delay charge in order to deploy the parachute.

Currently RocketPy does not have the functionality to define the parachute deploy charge as a fixed time event.

This can be either a fixed time from burnout, or fixed time from launch. This depends on if the motor is a core burner or end burner.

Describe the solution you'd like

I would like to be able to specify a time delay, here are the approaches I can come up with.

1. Adding T to the state vector given in Parachute.triggerfunc().
2. Adding key word support for flight phases, similar to apogee. IE: Launch then adding a lag.
3. Adding delay charge to motor characteristics.

Additional context

Here is the code base I am currently working to which this problem is relevant.
https://github.com/AidanPowers/AAE-439-Traj

I am willing to contribute to a fix, but this would be my first time contributing to a project so I may need some assistance.