Support `Custom Page Sizes` proposal

[vshymanskyy]

Feature suggestion

Currently, the WASM page size is fixed at 64KiB, which is rather expensive in some scenarios.

WebAssembly WG proposed a new feature to handle it nicely: https://github.com/WebAssembly/custom-page-sizes/blob/main/proposals/custom-page-sizes/Overview.md

This would allow generating really tiny wasm modules :raised_hands:

[CountBleck]

Hmm, this would require support in Binaryen for the proposal.