Outline timing manager IP core

[annikaolson]

This is a sub-issue of #323

Sketch out/create a general idea for an IP core and figure out connections, signals, and general logic.

Focus for the outline/things to keep note of:

• Interfaces between PWM generator and the sensor IPs
• Trigger is based on PWM carrier high and low signals
• Receives done signals based on the selected/configured sensors
• Keeps track of acquisition time per sensor (focus on more later)