Start pulling out IO thread and IO implementation

src/termio.zig

@@ -0,0 +1,17 @@
+//! IO implementation and utilities. The IO implementation is responsible
+//! for taking the config, spinning up a child process, and handling IO
+//! with the termianl.
+
+pub const Exec = @import("termio/Exec.zig");
+pub const Options = @import("termio/Options.zig");
+pub const Thread = @import("termio/Thread.zig");
+
+/// The implementation to use for the IO. This is just "exec" for now but
+/// this is somewhat pluggable so that in the future we can introduce other
+/// options for other platforms (i.e. wasm) or even potentially a vtable
+/// implementation for runtime polymorphism.
+pub const Impl = Exec;
+
+test {
+    @import("std").testing.refAllDecls(@This());
+}