add prompt presets

[tarekziade]

Let's add dynamic presets:

• presets for all
• per project

[sayakpaul]

We could also require each repo to have "review.md" so that there's some amount of human involvement because writing those rules is an experience-driven act I believe.

[sayakpaul]

From @tarekziade

Right now it's a list of hardcoded presets
In the ui
The goal is to move them in the repo yaml file
So each project can have its presets