perf: add PooledHashSet and PooledStringBuilder

[TimothyMakkison]

Use PooledHashSet and PooledStringBuilder, I'm only using it for DocPrinter.Output and PropagateBreaks.alreadyVisitedSet as they get to upwards of 50,000 items. I don't reuse very large objects to prevent cases where a massive file creates some large objects and they are never garbage collected, eating up space.

I'll look into benchmarking this change with a real world large repo.

Are there any instances where csharpier is kept running for a long time? This change is beneficial for projects with lots of medium sized files but passively uses more memory. I'm a bit worried this will eat up 64 MB when using csharpier as an extension.

I can mitigate this with a cleanup function if needed.

Related

Benchmarks

Before

Method	Mean	Error	StdDev	Median	Gen0	Gen1	Allocated
Default_CodeFormatter_Tests	103.5 ms	2.05 ms	3.70 ms	101.9 ms	2000.0000	1000.0000	31.07 MB
Default_CodeFormatter_Complex	190.2 ms	3.41 ms	6.31 ms	188.3 ms	5000.0000	2000.0000	54.57 MB

After

Method	Mean	Error	StdDev	Gen0	Gen1	Gen2	Allocated
Default_CodeFormatter_Tests	92.99 ms	1.651 ms	1.544 ms	3000.0000	1666.6667	333.3333	27.01 MB
Default_CodeFormatter_Complex	173.29 ms	2.924 ms	5.420 ms	5000.0000	2000.0000	-	49.65 MB