all: simplify wasm-tools-go dependency

- add internal/wasm-tools/go.mod file to depend on wasm-tools-go
- copy package cm into src/internal/cm
- remove wasm-tools-go "vendor" submodule

internal/tools: fix typo

go.{mod,sum}, internal/tools: add wit-bindgen-go to tools

GNUmakefile: use go run for wit-bindgen-go

GNUmakefile: add tools target to go:generate tools binaries in internal/tools

GNUmakefile: add .PHONY for lint and spell

GNUmakefile, internal/cm: vendor package cm into internal/cm

go.{mod,sum}: update wasm-tools-go to v0.1.4

internal/wasi: use internal/cm package

remove submodule src/vendor/github.com/ydnar/wasm-tools-go

GNUmakefile: add comment documenting what wasi-cm target does

go.{mod,sum}: remove toolchain; go mod tidy

go.mod: revert to Go 1.19

go.mod: go 1.19

go.{mod,sum}, internal/{tools,wasm-tools}: revert root go.mod file to go1.19

Create a wasm-tools specific module that can require go1.22 for wasm-tools-go.

src/internal/cm/option.go

@@ -0,0 +1,44 @@
+package cm
+
+// Option represents a Component Model [option<T>] type.
+//
+// [option<T>]: https://component-model.bytecodealliance.org/design/wit.html#options
+type Option[T any] struct{ option[T] }
+
+// None returns an [Option] representing the none case,
+// equivalent to the zero value.
+func None[T any]() Option[T] {
+	return Option[T]{}
+}
+
+// Some returns an [Option] representing the some case.
+func Some[T any](v T) Option[T] {
+	return Option[T]{
+		option[T]{
+			isSome: true,
+			some:   v,
+		},
+	}
+}
+
+// option represents the internal representation of a Component Model option type.
+// The first byte is a bool representing none or some,
+// followed by storage for the associated type T.
+type option[T any] struct {
+	isSome bool
+	some   T
+}
+
+// None returns true if o represents the none case.
+func (o *option[T]) None() bool {
+	return !o.isSome
+}
+
+// Some returns a non-nil *T if o represents the some case,
+// or nil if o represents the none case.
+func (o *option[T]) Some() *T {
+	if o.isSome {
+		return &o.some
+	}
+	return nil
+}