Bastard Keyboards: upstream recent changes (#18903)

* bastardkb: cleanup blackpill configuration

Fixes #17

* bastardkb: fix splinky configuration

The pinout of the splinky changed between the last beta batch, and the
production one. This commit updates the keyboard definition to support
the new pinout by default, while offering backward compatibility.

Define `SPLINKY_BETA_PINOUT` to build the firmware with pre-production
pinout.

Fixes #15

* bastardkb: add support for STeMCell

* Update scylla/tbkmini/skeletyl outdated readmes

* bastardkb/dilemma: enable circular scroll

* bastardkb/dilemma: add initial version of the `via` keymap

* bastardkb/dilemma/assembled: add new keyboard

Fixes #20

* bastardkb/dilemma: remove elite-c

* Initial support for the Dilemma 3x5+3 Assembled RGB

* Address code review comments

* Address more comments

* Address review comments

* Address more nits

* bastardkb: split splinky-based keyboards to distinguish between Splinky v2 and v3 pinout

keyboards/bastardkb/dilemma/readme.md

@@ -3,12 +3,14 @@
 A very small keyboard made for ergonomic enthusiasts.
 
 -   Keyboard Maintainer: [Bastard Keyboards](https://github.com/Bastardkb/)
--   Hardware Supported: elite-C V4, Splinky
+-   Hardware Supported: RP2040-based controller (_eg._ Splinky, Elite-c, ...)
 -   Hardware Availability: [Bastardkb.com](https://bastardkb.com/)
 
+A pre-assembled version (with embedded controller) is also available.
+
 Make example for this keyboard (after setting up your build environment):
 
-    make bastardkb/dilemma/elitec:default
-    make bastardkb/dilemma/splinky:default
+    make bastardkb/dilemma/3x5_2/splinky:default
+    make bastardkb/dilemma/3x5_2/assembled:default
 
 See the [keyboard build instructions](http://docs.bastardkb.com/)