Suport passing arbitrary llvm arguments (#271)

- Support for passing LLVM command line options via the prcoess input or
providing one or more `--llvm-arg='..'` resolc CLI flag. This allows
more fine-grained control over the LLVM backend configuration.
- Make LLVM initialization idempotent.

---------

Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

Cargo.lock

@@ -8368,6 +8368,7 @@ dependencies = [
  "hex",
  "inkwell",
  "itertools 0.14.0",
+ "libc",
  "num",
  "polkavm-common 0.21.0",
  "polkavm-disassembler",