[WIp] Alp encoding support

[sdf-jkl]

Which issue does this PR close?

• Closes [Parquet] Prototype ALP encoding #8748 .

Rationale for this change

check issue

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[alamb]

amaaazing

[sdf-jkl]

@alamb I worked with codex on replicating the c++ implementation reviewing commit by commit.

I'll do one final read myself, but this should be ready for initial review.

[alamb]

Thank you -- I will put this on my short list to reivew I was out last week

[devanbenz]

A few comments

[sdf-jkl]

@devanbenz Sorry for taking so long to address your comments. I'll make sure to work on it this week!

[alamb]

The final spec is

• GH-533: Add ALP (Adaptive Lossless floating-Point) encoding specification parquet-format#557

[devanbenz]

Comment about header regarding publication of spec.

[sdf-jkl]

Thanks @devanbenz, I finally addressed your reviews!

[devanbenz]

Thanks @devanbenz, I finally addressed your reviews!

Please cargo fmt the code 🫡

[sdf-jkl]

I swear I did 😿
Had to run

cargo fmt -p parquet --  --config skip_children=true `find ./parquet -name "*.rs" \! -name format.rs`

5e5c8d2