Don't require Store in Instance constructor (#810)

* Don't require `Store` in `Instance` constructor

This can be inferred from the `Module` argument. Additionally add a
`store` accessor to an `Instance` in case it's needed to instantiate
another `Module`.

cc #708

* Update more constructors

* Fix a doctest

* Don't ignore store in `wasm_instance_new`

* Run rustfmt

crates/test-programs/tests/wasm_tests/runtime.rs

@@ -61,7 +61,7 @@ pub fn instantiate(data: &[u8], bin_name: &str, workspace: Option<&Path>) -> any
         })
         .collect::<Result<Vec<_>, _>>()?;
 
-    let instance = Instance::new(&store, &module, &imports).context(format!(
+    let instance = Instance::new(&module, &imports).context(format!(
         "error while instantiating Wasm module '{}'",
         bin_name,
     ))?;

crates/test-programs/wasi-tests/Cargo.lock

@@ -17,7 +17,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "wasi-tests"
-version = "0.7.0"
+version = "0.9.0"
 dependencies = [
  "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
  "more-asserts 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",