[ci] Various size snapshot enhancements

[eps1lon]

• renames material-size-bot to mui-pr-bot (explicit about material-ui <-> material, more generic about purpose)
• test @material-ui/lab build in test_build
• add @material-ui/lab to size snapshot
• add thousand sep to size snapshot table
• right align sizes in size snapshot table

[mui-pr-bot]

@material-ui/lab: parsed: +Infinity%, gzip: +Infinity%

Details of bundle changes.

Comparing: f0cdca8...5096231

bundle	parsed diff	gzip diff	prev parsed	current parsed	prev gzip	current gzip
@material-ui/core/Paper	0.00%	0.00%	83,040	83,040	21,410	21,410
@material-ui/core/Paper.esm	0.00%	0.00%	76,728	76,728	20,462	20,462
@material-ui/core	0.00%	0.00%	484,797	484,797	130,083	130,083
@material-ui/core/styles/createMuiTheme	0.00%	0.00%	16,235	16,235	5,159	5,159
@material-ui/lab	+Infinity%:small_red_triangle:	+Infinity%:small_red_triangle:	0	295,473	0	86,174
@material-ui/styles	0.00%	0.00%	63,755	63,755	18,119	18,119
@material-ui/system	0.00%	0.00%	15,915	15,915	3,938	3,938
colorManipulator	0.00%	0.00%	2,290	2,290	838	838
Button	0.00%	0.00%	212,888	212,888	61,970	61,970
Modal	0.00%	0.00%	211,086	211,086	61,681	61,681
@material-ui/core/Popper	0.00%	0.00%	146,815	146,815	46,826	46,826
@material-ui/core/useMediaQuery	0.00%	0.00%	9,386	9,386	3,563	3,563
docs.main	0.00%	0.00%	675,841	675,841	204,947	204,947
docs.landing	0.00%	0.00%	48,963	48,963	10,275	10,275
packages/material-ui/build/umd/material-ui.production.min.js	0.00%	0.00%	320,431	320,431	84,703	84,703

Generated by 🚫 dangerJS against 5096231