This adds `RuntimeConfig.WithFeatureMutableGlobal(enabled bool)`, which
allows disabling of mutable globals. When disabled, any attempt to add a
mutable global, either explicitly or implicitly via decoding wasm will
fail.
To support this, there's a new `Features` bitflag that can allow up to
63 feature toggles without passing structs.
While here, I fixed a significant performance problem in decoding
binary:
Before
```
BenchmarkCodecExample/binary.DecodeModule-16 184243 5623 ns/op 3848 B/op 184 allocs/op
```
Now
```
BenchmarkCodecExample/binary.DecodeModule-16 294084 3520 ns/op 2176 B/op 91 allocs/op
```
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This moves to a new end-user API under the root package `wazero`. This
simplifies call sites while hardening function calls to their known
return value. Most importantly, this moves most logic internal, as
noted in the RATIONALE.md.
Ex.
```go
// Read WebAssembly binary containing an exported "fac" function.
source, _ := os.ReadFile("./tests/engine/testdata/fac.wasm")
// Decode the binary as WebAssembly module.
mod, _ := wazero.DecodeModuleBinary(source)
// Initialize the execution environment called "store" with Interpreter-based engine.
store := wazero.NewStore()
// Instantiate the module, which returns its exported functions
functions, _ := store.Instantiate(mod)
// Get the factorial function
fac, _ := functions.GetFunctionI64Return("fac")
// Discover 7! is 5040
fmt.Println(fac(context.Background(), 7))
```
PS I changed the README to factorial because the wat version of
fibonacci is not consistent with the TinyGo one!
Signed-off-by: Adrian Cole <adrian@tetrate.io>
Co-authored-by: Takaya Saeki <takaya@tetrate.io>
Co-authored-by: Takeshi Yoneda <takeshi@tetrate.io>
