fix bazelrun jvmflags, add list attribute

[plaird]

Two updates:

• New attribute bazelrun_jvm_flag_list is the new form of bazelrun_jvm_flags but is more bazel-like: it is an array of JVM args, instead of a space separated string
• Discovered that ADD_OPENS and ADD_EXPORTS bazel run script variables were not working correctly in some cases. There was no delineation between them and JVM_FLAGS and so in some cases jvm flags were being processed as ADDs. Removed those two variables since ADDs can just be treated as additional JVM_FLAGS in a single list.