BUMP: update rusm to the upstream rust compiler

* no more [link] attribute
Immediate bit range checks

Fix range checks for all immediate in instructions, most of them were wrong.

is_u32n => check that the unsigned integer fits in n bits.
is_i32n  => check that the signed integer fits in n bits.

As modified immediate constants are not implemented yet, we stick to 8 bits
immediate.
Refactor assembler: get_label_index

get_label_index searches for a given label in the assembler's list of labels
in the code. The label _needs_ to be found.
Move src/utils/rs to src/function.rs

Let the function module handle code in memory.
Support for adr instruction

This patch includes the code for patching the instruction with a label.

Labels need to be in a 8 bits range.