feat(boards): Update for mikoto board definition (#1946)

* Set default revision to 5.20
* update mikoto board defs
* add revision info to mikoto.zmk.yml
* use zephyr aliases to handle mikoto_520
* enable pull-ups for on-board i2c

app/boards/arm/mikoto/mikoto.zmk.yml

@@ -0,0 +1,16 @@
+file_format: "1"
+id: mikoto
+name: Mikoto
+type: board
+arch: arm
+outputs:
+  - usb
+  - ble
+url: https://github.com/zhiayang/mikoto
+exposes: [pro_micro]
+revisions:
+  - "5.20"
+  - "6.1"
+  - "6.3"
+  - "7.2"
+default_revision: "5.20"