Add full code for $scheduler1 and $scheduler2 examples

[frank-emrich]

The third section of the explainer currently compares task scheduling using resume/suspend vs switch using two example modules, $scheduler1 and $scheduler2. The explainer only contains a skeleton of the actual code.

This PR adds .wast files containing full code for these modules and links to them in the explainer. The code is carefully written to follow the structure shown in the explainer.

The code already follows the syntax update coming in #81.

Based on earlier versions of the code created by @dhil.

[dhil]

Thanks! Lets run and merge this after #81.

[dhil]

Thanks! I have confirmed (locally) that they both run with the latest version of the reference interpreter.

For scheduler1.wast I get:

0 : i32
1 : i32
0 : i32
2 : i32
1 : i32
3 : i32
2 : i32
3 : i32

For scheduler2.wast I get:

0 : i32
1 : i32
0 : i32
2 : i32
1 : i32
3 : i32
2 : i32
3 : i32

which I believe is the expected output.