Switch to pooling copy-on-write instantiation strategy for WASM (#11232)

* 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

substrate/client/executor/src/lib.rs

@@ -51,6 +51,9 @@ pub use wasmi;
 
 pub use sc_executor_common::{error, sandbox};
 
+#[cfg(feature = "wasmtime")]
+pub use sc_executor_wasmtime::InstantiationStrategy as WasmtimeInstantiationStrategy;
+
 /// Extracts the runtime version of a given runtime code.
 pub trait RuntimeVersionOf {
 	/// Extract [`RuntimeVersion`](sp_version::RuntimeVersion) of the given `runtime_code`.