impr(layouts): add basic support for thumb alpha keys (@zigotica)

[zigotica]

Description

ROW 5 in alternate keymaps allow for alphas in thumb keys.

• These keymaps MUST include two keys in row 5, an alpha and a space, or a space and an alpha.
• Alpha key is rendered with the regular alpha size.
• Layout name is automatically added in the space key.
• Added keymaps using alphas in thumbs: anishtro, BEAKL_Zi, MALTRON, PRSTEN and RSTHD

Checks

• Made sure all physical layouts work for alternate and classic keymaps. Attaching images for all of them in the PR.

• Adding quotes?
  • Make sure to include translations for the quotes in the description (or another comment) so we can verify their content.
• Adding a language or a theme?
  • If is a language, did you edit _list.json, _groups.json and add languages.json?
  • If is a theme, did you add the theme.css?
    • Also please add a screenshot of the theme, it would be extra awesome if you do so!
• Check if any open issues are related to this PR; if so, be sure to tag them below.
• Make sure the PR title follows the Conventional Commits standard. (https://www.conventionalcommits.org for more info)
• Make sure to include your GitHub username prefixed with @ inside parentheses at the end of the PR title.

Closes #2291

[Miodec]

Please move the layouts to the bottom of the list file.

[Miodec]

Other than those two I think its all good.

[zigotica]

Please move the layouts to the bottom of the list file.

moved

[Miodec]

Thanks