feat: initial Earthly CI (AztecProtocol/aztec-packages#5069)

Introduces earthly as an alternative CI that hopes to eventually replace
our current build-system.

https://docs.earthly.dev/ is a build system that combines Makefiles and
Dockerfiles. This is basically exactly what our system needed, IMO, and
has some nice things figured out. Hope is to reduce complexity of
working with the build system by a good chunk.

Core changes:
- we have a github actions CI that runs a single end to end test inside
earthly for arm64 and x86_64
- new Earthfile's now mirror the Dockerfile's, notable differences:
  - we build our own foundry package for ARM support
  - we build our own wasi-sdk package for ARM support
- grumpkin SRS is no longer generated on the spot, but downloaded like
bn254 SRS
- we don't inject any commit hashes for Noir as this would cause
spurious rebuilds as any difference stops caching, instead we inject a
content hash (to be revisited)

 Side changes:
- since we build our own wasi-sdk 21 package, and it is clang18, some
compilation workarounds
  - allow specifying a different nargo and acvm binary in build
  - small output tweaks

---------

Co-authored-by: Charlie Lye <karl.lye@gmail.com>
Co-authored-by: Innokentii Sennovskii <isennovskiy@gmail.com>
Co-authored-by: Cody Gunton <codygunton@gmail.com>
Co-authored-by: Alex Gherghisan <alexghr@users.noreply.github.com>
Co-authored-by: Mitchell Tracy <mitchell@aztecprotocol.com>
Co-authored-by: Jan Beneš <janbenes1234@gmail.com>
Co-authored-by: esau <152162806+sklppy88@users.noreply.github.com>
Co-authored-by: Facundo <fcarreiro@users.noreply.github.com>
Co-authored-by: josh crites <critesjosh@gmail.com>
Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com>
Co-authored-by: Álvaro Rodríguez <sirasistant@gmail.com>
Co-authored-by: Ilyas Ridhuan <ilyas@aztecprotocol.com>

.aztec-sync-commit

@@ -1 +1 @@
-9cc32cb5e4aaf03ea3457a8fcf3b38c1e39d3d04
+8e75fe5c47250e860a4eae4dbf0973c503221720

.github/scripts/wasm-bindgen-install.sh

@@ -6,7 +6,7 @@ cd $(dirname "$0")
 ./cargo-binstall-install.sh
 
 # Install wasm-bindgen-cli.
-if [ "$(wasm-bindgen --version | cut -d' ' -f2)" != "0.2.86" ]; then
+if [ "$(wasm-bindgen --version &> /dev/null | cut -d' ' -f2)" != "0.2.86" ]; then
   echo "Building wasm-bindgen..."
   cargo binstall wasm-bindgen-cli@0.2.86 --force --no-confirm
 fi