Allow experimental options in preinitialized contexts.

Adds a flag which allows use of experimental Truffle
context options in preinitialized contexts.

Fixes and closes oracle#10790

Signed-off-by: Sam Gammon <sam@elide.dev>

Author: sgammon

truffle/src/com.oracle.truffle.polyglot/src/com/oracle/truffle/polyglot/PolyglotContextConfig.java

@@ -235,7 +235,7 @@ private static Map<String, String> computeCommonOptions(Map<String, String> opti
                         null,
                         false,
                         false,
-                        false,
+                        Boolean.getBoolean("polyglot.image-build-time.PreinitializeAllowExperimentalOptions"),
                         null,
                         Collections.emptyMap(),
                         Collections.emptySet(),