only build intersection props that can reduce it to never

[Max Schwenk (maschwenk)]

Fixes #64474 (part 2, #64475 is part 1). doesnt depend on #64475

getReducedType checks whether an intersection reduces to never by calling getPropertiesOfUnionOrIntersectionType, which creates the combined property (and the intersection of its types) for every name in the intersection and keeps all of them around. but a combined property can only reduce the intersection if one of the constituent properties has a literal type or is private

so this moves the loop in createUnionOrIntersectionProperty that collects each constituent's property of a name into collectUnionOrIntersectionPropertyParts, and both use it. getReducedType looks at what it collected and only creates the combined property when it could reduce the intersection. theres no second copy of the checking logic. the code change is about 80 lines, the rest of the diff is one test and its baselines

similar goal to #53346, but instead of stopping early it skips creating the properties that can't reduce, which is where the memory goes

this PR alone vs main (typescript-benchmarking, median of 3):

	heap, 4 checkers	peak rss, 4 checkers	check, 4 checkers	heap, single	check, single
mui-docs	−41.8%	−38.2%	−38.9%	−33.7%	−28.8%
Compiler-Unions	−4.7%	−3.0%	0.0%	−5.1%	−3.8%
webpack	−2.5%	+1.9%	−3.9%	−2.9%	−2.7%
xstate-main	−1.2%	−0.9%	+3.6%	−0.9%	+0.5%
vscode	−0.4%	−0.7%	−2.2%	−0.3%	+0.8%
Compiler	−1.8%	−1.0%	+1.4%	−0.4%	−1.2%

mui-docs gets the big win since its styling types build some really big intersections. the check times on the small projects are within run to run noise. raw results and scripts: https://gist.github.com/maschwenk/c83d9185c6961b6fb43d7d071ef39cf6

i also tried an even simpler check, create the property for any name more than one constituent has (d33ab85). less code, but on our 37k-file program it held 0.28 GiB more heap, so i went back

full go suite passes (also multiple checkers and -race), lint and format are clean. added intersectionNeverReductionByProperty.ts with baselines generated on unmodified main. it covers literal/boolean/template literal discriminants, optional and never props, private vs protected, instantiations of the same generic class, generic aliases and type params with union constraints

• associated issue in Backlog: checker builds member tables and intersection props it never uses #64474, not triaged yet
• up to date with main
• tests pass (go test ./... in tsc, same thing hereby test runs)
• hereby lint
• hereby check:format
• new tests

used claude code to help write this, ive reviewed it