Fix JSON5 parsing to make block comments non-greedy

Author: mikera

convex-core/src/main/antlr4/convex/core/json/reader/antlr/JSON.g4

@@ -84,7 +84,7 @@ fragment EXP
 
 // Multi-line comments (ignored)
 MULTILINE_COMMENT
-	: '/*' .* '*/' -> skip
+	: '/*' .*? '*/' -> skip
 	;
 
 // Single-line comments (ignored)

convex-core/src/test/java/convex/core/utils/JSONUtilsTest.java

@@ -76,6 +76,7 @@ public void testParse() {
 		assertEquals(Strings.NIL,JSONUtils.parse("\"nil\""));
 
 		assertSame(Maps.empty(),JSONUtils.parse("{}"));
+		assertSame(Maps.empty(),JSONUtils.parse("{ /* foo */ } /*bar*/ /*baz*/"));
 		assertEquals(Maps.of(Strings.NIL,1),JSONUtils.parse("{\"nil\": 1}"));
 		assertEquals(Maps.of(Strings.EMPTY,Vectors.empty()),JSONUtils.parse("{\"\": []}"));