feat(developer): Add kmc module to generate help documentation charts of all "gesture" keys

[darcywong00]

To address keymanapp/keyboards#2213, a prototype was started in keymanapp/keyboards#2594

I'll recap the review comments from the PR here:

• move the tool from keymanapp/gestureChart to keymanapp/keyman, and ideally we will integrate this into kmc as a kmc module. Then we could merge it in 18.0.
• TouchLayoutFileReader should be used to read the keyman touch layout file because that does validation and normalization of content
• For handling vertical line character, we want to use escapeMarkdownChar function in Developer
• Can cleanup console warnings about not handling T_ keys in the touch layout (not needed) 🔗 chore: Ignore T_ keys gestureChart#1
• One other challenge is that while this tool generates Markdown, we don't currently support Markdown in keyboard documentation welcome.htm, which is where this content belongs (not just on help.keyman.com).