Test moves, items, and abilities in battle

Thank you to SBird for providing mgba-rom-test binaries and Spikes/Toxic
Spikes tests!

Co-authored-by: sbird <sbird@no.tld>

ld_script_modern.txt

@@ -2,6 +2,7 @@ ENTRY(Start)
 
 gNumMusicPlayers = 4;
 gMaxLines = 0;
+gInitialMainCB2 = CB2_InitCopyrightScreenAfterBootup;
 
 SECTIONS {
     . = 0x2000000;