1UpKeyboards Pi60 Layout Additions (qmk#21874)

* [refactor] rename LAYOUT_60_ansi to LAYOUT_all

* [enhancement] add LAYOUT_60_ansi

* [enhancement] add LAYOUT_60_ansi_split_bs_rshift

* [enhancement] add LAYOUT_60_ansi_tsangan

* [enhancement] add LAYOUT_60_tsangan_hhkb

* [enhancement] add LAYOUT_60_iso

* [enhancement] add LAYOUT_60_iso_split_bs_rshift

* [enhancement] add LAYOUT_60_iso_tsangan

* [enhancement] add LAYOUT_60_iso_tsangan_split_bs_rshift

* [enhancement] enable Community Layout support

* [enhancement] add LAYOUT_60_hhkb

* [enhancement] add LAYOUT_60_ansi_arrow

* [enhancement] add LAYOUT_60_iso_arrow

* [docs] add layout/matrix diagram

Author: noroadsleft