pallet_revive: Switch to 64bit RISC-V (#6565)

This PR updates pallet_revive to the newest PolkaVM version and adapts
the test fixtures and syscall interface to work under 64bit.

Please note that after this PR no 32bit contracts can be deployed (they
will be rejected at deploy time). Pre-deployed 32bit contracts are now
considered defunct since we changes how parameters are passed for
functions with more than 6 arguments.

## Fixtures

The fixtures are now built for the 64bit target. I also removed the
temporary directory mechanism that triggered a full rebuild every time.
It also makes it easier to find the compiled fixtures since they are now
always in `target/pallet-revive-fixtures`.

## Syscall interface

### Passing pointer

Registers and pointers are now 64bit wide. This allows us to pass u64
arguments in a single register. Before we needed two registers to pass
them. This means that just as before we need one register per pointer we
pass. We keep pointers as `u32` argument by truncating the register.
This is done since the memory space of PolkaVM is 32bit.

### Functions with more than 6 arguments

We only have 6 registers to pass arguments. This is why we pass a
pointer to a struct when we need more than 6. Before this PR we expected
a packed struct and interpreted it as SCALE encoded tuple. However, this
was buggy because the `MaxEncodedLen` returned something that was larger
than the packed size of the structure. This wasn't a problem before. But
now the memory space changed in a way that things were placed at the
edges of the memory space and those extra bytes lead to an out of bound
access.

This is why this PR drops SCALE and expects the arguments to be passed
as a pointer to a `C` aligned struct. This avoids unaligned accesses.
However, revive needs to adapt its codegen to properly align the
structure fields.

## TODO
- [ ] Add multi block migration that wipes all existing contracts as we
made breaking changes to the syscall interface

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Co-authored-by: GitHub Action <[email protected]>