Make the fuel-vm no-std or WASM/RiscV compatible

[SilentCicero]

Abstract

We need to make the entire fuel-vm implementation RiscV compatible for fraud proving.

This would also allow for better browser, debugging and educational tools for the FuelVM.

Currently Compatible

• fuel-asm
• fuel-types
• fuel-merkle
• fuel-storage
• fuel-crypto
• fuel-tx (uses fuel-crypto)
• fuel-vm (uses fuel-tx)

Related:
#443
#533

[Dentosal]

Related: getrandom doesn't support freestanding riscv64, so we'll need a fallback rng or some other way to work around that.

[DefiCake]

Just reporting the state of compatibility with risc0 / riscV, fuel-crypto is compiling correctly now.

Currently, the build process complains about fuel-tx.

error[E0277]: the trait bound `Transaction: fuel_tx::FormatValidityChecks` is not satisfied
   --> /Users/mad/fuel/vm/fuel-vm/src/checked_transaction.rs:577:22
    |
577 | impl IntoChecked for Transaction {
    |                      ^^^^^^^^^^^ the trait `fuel_tx::FormatValidityChecks` is not implemented for `Transaction`
    |
    = help: the following other types implement trait `fuel_tx::FormatValidityChecks`:
              fuel_tx::Create
              fuel_tx::Mint
              fuel_tx::Script
... 

Not very experienced in rs, but it looks to me as the FormatValidityChecks is only available under std:

#[cfg(feature = "std")]
impl FormatValidityChecks for Transaction {
...

[Dentosal]

This is almost achieved in #536, which makes the VM itself runnable under no_std conditions but still lacks some of the RiscV-specific stuff.

[xgreenx]

After https://danielmangum.com/posts/risc-v-bytes-rust-cross-compilation/, we are able to compile fuel-vm and fuel-tx into WASM and RiscV.

cargo build --target wasm32-unknown-unknown --no-default-features -p fuel-tx --features alloc
cargo build --target wasm32-unknown-unknown --no-default-features -p fuel-vm --features alloc
cargo build --target riscv64imac-unknown-none-elf --no-default-features -p fuel-tx --features alloc
cargo build --target riscv64imac-unknown-none-elf --no-default-features -p fuel-vm --features alloc

Closing this issue=)