Try loading patterns from .html files in FSE themes

[bobbingwide]

For the thisis theme I exported the templates and template parts as .htm files. These are not detected by Gutenberg so do not get used as templates and template-parts. The end user will therefore have to create their own templates.
This might not be particularly helpful. Perhaps we can treat these files as candidates for patterns.

[bobbingwide]

Requirements

• To be able to load patterns directly from files in the active / installed themes
• To automatically set the pattern name and pattern properties from the file and/or contents

Proposed solution

• Develop a class called OIK_Patterns_From_Htm
• Load any *.htm files from block-templates and/or block-template-parts
• Use the theme name to register the pattern category
• Use the file name for the pattern name
• Use the file name for the pattern title
• Test with existing files from the thisis theme

[bobbingwide]

I tested with Gutenberg 10.4.1
After loading the patterns from both block-templates and block-template-parts the browser became unresponsive and eventually Google Chrome went "Aw snap!"

I haven't investigated the problem yet.

[bobbingwide]

This logic works but I want to improve it. Raising a new issue.

[bobbingwide]

The new issue #4 has now been repurposed. Reopening this to improve the logic to load .html files from the patterns directory, using subfolders to represent categories. Perhaps it should also use the patterns.json file if present.

• Improve the pattern's title
• Load files from subdirectories
• Determine the categories based on sub-folder structure
• Use patterns.json file if present