[docs] Run the TypeScript demos

[oliviertassinari]

This change is running the TypeScript demos when the code variant is selected. It will significantly improve the workflow. Now, we can iterate on the TypeScript demo variants FIRST, then run docs:typescript:formatted. We do no longer have to worry about the JavaScript demos.

I have only migrated the snackbar

[mui-pr-bot]

Details of bundle changes.

Comparing: 240dc18...906df8f

bundle	parsed diff	gzip diff	prev parsed	current parsed	prev gzip	current gzip
@material-ui/core	0.00%	0.00%	349,839	349,839	89,879	89,879
@material-ui/core/Paper	0.00%	0.00%	67,853	67,853	19,820	19,820
@material-ui/core/Paper.esm	0.00%	0.00%	60,184	60,184	18,563	18,563
@material-ui/core/Popper	0.00%	0.00%	30,463	30,463	10,530	10,530
@material-ui/core/styles/createMuiTheme	0.00%	0.00%	17,364	17,364	5,726	5,726
@material-ui/core/useMediaQuery	0.00%	0.00%	2,469	2,469	1,041	1,041
@material-ui/lab	0.00%	0.00%	147,758	147,758	43,621	43,621
@material-ui/styles	0.00%	0.00%	53,105	53,105	15,433	15,433
@material-ui/system	0.00%	0.00%	17,136	17,136	4,525	4,525
Button	0.00%	0.00%	87,927	87,927	26,054	26,054
Modal	0.00%	0.00%	82,035	82,035	24,552	24,552
colorManipulator	0.00%	0.00%	3,232	3,232	1,299	1,299
docs.landing	0.00%	0.00%	49,899	49,899	10,803	10,803
docs.main	+0.02% 🔺	0.00%	645,314	645,433	200,459	200,465
packages/material-ui/build/umd/material-ui.production.min.js	0.00%	0.00%	298,242	298,242	82,697	82,697

Generated by 🚫 dangerJS against 906df8f

[eps1lon]

Very nice. With this change yarn docs:typescript isn't useful anymore. We can merge it later into docs/scripts/formattedTSDemos.

[oliviertassinari]

We should be good now.