Optimize release builds for runtime performance

[maciektr]

• Enable thin LTO
• Set codegen-units to 1
• Use mimalloc

On OZ:
Before:

Benchmark 1: /Users/maciektr/Projects/forks/starknet-foundry/target/release/snforge test --profile=release --fuzzer-seed=11067975336895813681 -w
  Time (mean ± σ):     45.516 s ±  0.186 s    [User: 324.214 s, System: 24.364 s]
  Range (min … max):   45.297 s … 45.776 s    5 runs

Thin LTO:

Benchmark 1: /Users/maciektr/Projects/forks/starknet-foundry/target/release/snforge test --profile=release --fuzzer-seed=11067975336895813681 -w
  Time (mean ± σ):     43.745 s ±  0.270 s    [User: 306.863 s, System: 24.961 s]
  Range (min … max):   43.436 s … 44.037 s    5 runs

Fat LTO:

Benchmark 1: /Users/maciektr/Projects/forks/starknet-foundry/target/release/snforge test --profile=release --fuzzer-seed=11067975336895813681 -w
  Time (mean ± σ):     43.460 s ±  0.414 s    [User: 304.455 s, System: 24.738 s]
  Range (min … max):   43.084 s … 44.157 s    5 runs

Thin LTO + MiMalloc:

Benchmark 1: /Users/maciektr/Projects/forks/starknet-foundry/target/release/snforge test --profile=release --fuzzer-seed=11067975336895813681 -w
  Time (mean ± σ):     38.304 s ±  0.392 s    [User: 271.223 s, System: 7.359 s]
  Range (min … max):   37.938 s … 38.965 s    5 runs