* Allow HMX components in markdown
This adds support for HMX components in markdown. The mechanism for importing is via frontmatter. We could do this differently (setup script maybe?) but since this was the easiest to implement I thought it was a good first-pass option.
* Remove node-fetch from snowpack config
* Assert that the runtime is created successfully
* Add back in the micromark extension for encoding entities
* Encode both codeTextData and codeFlowValue
* Install snowpack app's deps
