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

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](https://github.com/keymanapp/keyman/blob/5062bbad984760a40e5ee3d012b65d54d805db1d/developer/src/common/web/utils/src/markdown.ts#L2-L21)
- [ ] Can cleanup console warnings about not handling `T_` keys in the touch layout (not needed) :link: keymanapp/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).

Review the prototype in keymanapp/gestureChart and PR keymanapp/keyboards#2594, then trace the proposed move into keymanapp/keyman. Check TouchLayoutFileReader, escapeMarkdownChar in developer/src/common/web/utils/src/markdown.ts, and the keyboard documentation welcome.htm path. Done means the chart generator is integrated as a kmc module with the listed review concerns addressed.

Written by the indexing model from the issue text.