Add Plangothic

**Font Project Git Repo URL:**
https://github.com/Fitzgerald-Porthmouth-Koenigsegg/Plangothic

**Super short description of the Font Family:**
An project based on extending Source Han Sans targeting to cover all of Unicode.

It currently covers all of CJK Unified Ideographs Extension G!

**Requirements:**

I understand that Google Fonts will publish only fonts that matches its requirements, and I can confirm the project meets them (by ticking the cases, or putting x between the square brackets in text mode):

- [x] The entire font project is licensed under the [OFL](https://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=OFL)
- [x] There is no "Reserved Font Name" mention in the OFL license
- [x] Family name is unique according to namecheck.fontdata.com
- [ ] The font supports at least [GF Latin Core glyphset](https://github.com/googlefonts/glyphsets/tree/main/GF_glyphsets/Latin/)
- [ ] The repository respect the [upstream repo structure](https://github.com/googlefonts/gf-docs/tree/main/Spec#upstream-repo-structure)
- [ ] The source files are available in the repository
- [ ] I read, agree and comply with the full [contributing requirements](https://github.com/google/fonts/blob/main/CONTRIBUTING.md)
- [ ] I am the author of the font or the author agreed to this submission
- [ ] I will maintain the repository

**Image:**

**Notes:**
I do not own this project, and I am unsure if the original copyright holders have signed the Google CLA. However this will be good project for Google Fonts to check up with, because it will be more "Noto" than the existing "Noto Sans CJK SC".