WASM: Introduce the [reveal] host function

Context

• Previous MR: !9671 (merged)
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This MR adds a new host function: reveal. Its purpose is to allow arbitrary (raw) reveal requests. As a consequence, if new reveal cases are added, they won’t need a dedicated host function to be made available for a kernel to use them.

This is only possible thanks to the addition of the L1 mechanism to determine whether or not a reveal request is enabled at a given L1 level.

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR