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GH-17682: [Format] Add Bool8 Canonical Extension Type (#43234)



### Rationale for this change

Closes: #17682

Arrow Boolean arrays store values as individual bits, which is a very compact representation but does not match the layout of many systems with which it interoperates. By adding an 8-bit Boolean extension type, zero-copy compatibility with many systems can be improved at the cost of large physical representation.

Go implementation: #43323
C++ / Python implementation: #43488

### What changes are included in this PR?

Proposal and documentation for `Bool8` canonical extension type.

### Are these changes tested?

N/A

### Are there any user-facing changes?

N/A

* GitHub Issue: #17682

Lead-authored-by: Joel Lubinitsky <joellubi@gmail.com>
Co-authored-by: Joel Lubinitsky <33523178+joellubi@users.noreply.github.com>
Co-authored-by: Felipe Oliveira Carvalho <felipekde@gmail.com>
Signed-off-by: Joel Lubinitsky <joellubi@gmail.com>