Add a new submodule: lab-grapher

It's code extracted from the Lab repo itself.
Use grapher code from the submodule instead of src directory

[#61295834]
Remove grapher code (some files were unused even by grapher itself)

[#61295834]
Create model controller without any model and wait for it
Create interactive components before model is loaded
Setup semantic layout just once, during interactive load
Setup exports controller just once (during interactive load)
Setup help tips just once (during interactive load)
Setup parent message API just once (during interactive load)
Clarify a few documentation items.
LatentHeat: rm “Reset Experiment” button & disable ‘Start adding heat'

Remove one of the Reset buttons from the Latent Heat interactives.

Disable 'Start adding heat' button in Latent Heat interactive after the first time it is clicked.

[#61563022][#61563190]

https://www.pivotaltracker.com/story/show/61563022
https://www.pivotaltracker.com/story/show/61563190
Remove time display from playback controller in Latent Heat interactives

[#61563608]
https://www.pivotaltracker.com/story/show/61563608
ITSI: Fix Concentration and Breathing
ITSI: Fix Making and Breaking Bonds (A+A->A2)
ITSI: Fix Making and Breaking Bonds (A+B->AB)
ITSI: Fix Dissociation Energy interactive
ITSI: Fix Dissociation (rites copy) interactive
ITSI: Fix Activation Energy 1 interactive
ITSI: Activation Energy 2 interactive

[#61170460]
ITSI: Activation Energy 3 interactive

[#61170538]