Keymap: Refactor symbols layer with layer tap workaround (#3520)

* Squash layout to fit on Planck

* Replace AST with PAST keycode so that it works with layer tap

* Review markups

quantum/keymap_extras/keymap_uk.h

@@ -132,6 +132,25 @@
 #define UK_ASTR KC_ASTR
 #define UK_QUOT KC_QUOT
 
+#define UK_P1 KC_P1
+#define UK_P2 KC_P2
+#define UK_P3 KC_P3
+#define UK_P4 KC_P4
+#define UK_P5 KC_P5
+#define UK_P6 KC_P6
+#define UK_P7 KC_P7
+#define UK_P8 KC_P8
+#define UK_P9 KC_P9
+#define UK_P0 KC_P0
+#define UK_PDOT KC_PDOT
+#define UK_PCMM KC_PCMM
+#define UK_PSLS KC_PSLS
+#define UK_PAST KC_PAST
+#define UK_PMNS KC_PMNS
+#define UK_PPLS KC_PPLS
+#define UK_PEQL KC_PEQL
+#define UK_PENT KC_PENT
+
 #define UK_TAB KC_TAB
 #define UK_ENT KC_ENT
 #define UK_LSFT KC_LSFT