Add support for mutable globals and sign extension instructions

[abizjak]

Task description

In Rust 1.70 the default code generation (that is not possible to override) has changed so that the emitted code can contain sign extension instructions not present in the MVP version.

See https://releases.rs/docs/1.70.0/#compatibility-notes for the changelog.

Since these instructions are a conservative extension we should support them since that is the simplest way forward to ensure compatibility with newer Rust versions, but this requires a protocol update.

See also rust-lang/rust#109807 for a tracking issue on why the behaviour cannot be disabled.

Followup tasks:

• Once this task is completed and the node is released with the new protocol version we must remove the mentions of Rust 1.69 from the documentation.

[abizjak]

It appears we already support mutable globals since they are part of the V1 Wasm spec.