feat!: ban BITS == 0

[DaniPopes]

This way too many branches for something that is practically useless. This should've never been allowed.

I'm pretty confident nobody is using this. If there is, we can always revert this.

[codspeed-hq]

Merging this PR will improve performance by 11.06%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 3 improved benchmarks
✅ 383 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	most_significant_bits/4096/4096	29 µs	26.1 µs	+10.98%
⚡	to/f32/4096	29.1 µs	26.3 µs	+10.97%
⚡	to/f64/4096	29.2 µs	26.3 µs	+11.06%

---

_{Comparing DaniPopes:ban-bits-zero (3851eb8) with main (bff85c8)}

[prestwich]

i'm generally in favor, however, this is a 2.0 change. are we planning a 2.0 release and if so, what else do we want in?

[prestwich]

related: #502

[DaniPopes]

Gonna wait for this