Disable code fence

[bmuenzenmeyer]

Make it so the codeblock fence can be disabled. This allows importing of raw text (or other content) directly into files.

<!-- README.md -->

[Some readme content here]

# Contributing

<!--
  CODEBLOCK_START
  {
    "value": "CONTRIBUTING.md",
    "codeFence": false
  }
-->

[Some contributing content here]

<-- CODEBLOCK_END -->

I'm realizing now that this would probably require a CODEBLOCK_START_[name] to prevent recursion (importing actions which now run on both markdown files).

[10hendersonm]

I'm realizing now that this would probably require a CODEBLOCK_START_[name] to prevent recursion (importing actions which now run on both markdown files).

Another idea that could get us partway: detect the presence of markdown-inject blocks in the resolved file and throw.

Or we could create a tree of .md files beforehand and walk up the tree, throwing if there are circular dependencies.