Add pxe test + convert prc_256.py to pure r2 (#16838)

test/scripts/palette.r2

@@ -0,0 +1,65 @@
+ec comment rgb:c50f1f
+ec usrcmt rgb:cccccc
+ec args rgb:c19c00
+ec fname rgb:c50f1f
+ec floc rgb:3a96dd
+ec fline rgb:3a96dd
+ec flag rgb:3a96dd
+ec label rgb:3a96dd
+ec help rgb:13a10e
+ec flow rgb:3a96dd
+ec flow2 rgb:0037da
+ec prompt rgb:c19c00
+ec offset rgb:13a10e
+ec input rgb:cccccc
+ec invalid rgb:e74856 . bold
+ec other rgb:cccccc
+ec b0x00 rgb:13a10e
+ec b0x7f rgb:3a96dd
+ec b0xff rgb:c50f1f
+ec math rgb:c19c00
+ec bin rgb:3a96dd
+ec btext rgb:c19c00
+ec push rgb:881798
+ec pop rgb:b4009e . bold
+ec crypto rgb:0037da
+ec jmp rgb:13a10e
+ec cjmp rgb:13a10e
+ec call rgb:16c60c . bold
+ec nop rgb:0037da
+ec ret rgb:c50f1f
+ec trap rgb:e74856 . bold
+ec ucall rgb:13a10e
+ec ujmp rgb:13a10e
+ec swi rgb:881798
+ec cmp rgb:3a96dd
+ec reg rgb:3a96dd
+ec creg rgb:3a96dd
+ec num rgb:c19c00
+ec mov rgb:cccccc
+ec func_var rgb:cccccc
+ec func_var_type rgb:0037da
+ec func_var_addr rgb:3a96dd
+ec widget_bg rgb:303030
+ec widget_sel rgb:c50f1f
+ec ai.read rgb:13a10e
+ec ai.write rgb:0037da
+ec ai.exec rgb:c50f1f
+ec ai.seq rgb:881798
+ec ai.ascii rgb:c19c00
+ec graph.box rgb:000000
+ec graph.box2 rgb:0037da
+ec graph.box3 rgb:881798
+ec graph.box4 rgb:767676
+ec graph.true rgb:13a10e
+ec graph.false rgb:c50f1f
+ec graph.trufae rgb:0037da
+ec graph.current rgb:0037da
+ec graph.traced rgb:c19c00
+ec gui.cflow rgb:c19c00
+ec gui.dataoffset rgb:c19c00
+ec gui.background rgb:0c0c0c
+ec gui.alt_background rgb:cccccc
+ec gui.border rgb:0c0c0c
+ec wordhl rgb:c50f1f
+ec linehl rgb:000080