* Switch to pooling copy-on-write instantiation strategy for WASM
* Fix benchmark compilation
* Fix `cargo fmt`
* Fix compilation of another benchmark I've missed
* Cleanups according to review comments
* Move `max_memory_size` to `Semantics`
* Set `memory_guaranteed_dense_image_size` to `max_memory_size`
* Rename `wasm_instantiation_strategy` to `wasmtime_instantiation_strategy`
* Update the doc-comments regarding the instantiation strategy
* Extend the integration tests to test every instantiation strategy
* Don't drop the temporary directory until the runtime is dropped in benchmarks
* Don't drop the temporary directory until the runtime is dropped in tests