perf(compute): pre-size SetLookupState memo tables

[fallintoplace]

Summary

• Pre-size the memo table used by SetLookupState from the value-set length.
• Use the memo table's 50% growth threshold when choosing the initial table size.
• Keep the other hash-state paths at their current zero-size hint.
• Add a benchmark for numeric and string value sets with unique and repeated values.

Benchmark

Apple M1 Pro. Compared with main at 6b039a76.

For a 64K unique value set:

Case	Main B/op	This change B/op	Main allocs/op	This change allocs/op
int64	8.66 MB	3.41 MB	58	52
string	10.13 MB	6.56 MB	64,099	64,062

The main benefit is avoiding repeated table growth and rehashing while building a large lookup set.

Checks

• go test ./arrow/compute/... -count=1
• go test -race ./arrow/compute/...
• go vet ./arrow/compute/internal/kernels