evalCodeBlocks should accept configuration from an HTML comment within the input markdown

[pskfyi]

This would allow individual markdown files to contain their own find/replace strings, register language handlers, and other configurations. Here is a concept for discussion purposes:

<!--config:evalCodeBlocks:yaml

  fileHandler:
    py: "./python/evaulate.ts"
  replace:
  - ["hello", "goodbye"]
  - ["world", "mars"]
-->
  
```py
print("hello world!")
```

import { evalCodeBlocks } from "./handy/md/script/evalCodeBlocks.ts"

const markdown = Deno.readTextFileSync("./myFile.md") // the file above with the HTML comment

const results = evalCodeBlocks(markdown)

assert(results[0] === "goodbye mars")