Re-examine and decide the granularity of localedata and cldrdata modules.

This comment from Alan/Mandy, respectively, should also be considered with this CR:

"One comment on the test Bug8038436 is that it sets java.ext.dirs on the
assumption that the locale and cldr data wouldn't be found. I suspect
this will need to be re-worked once we get to the point of linking
modules into the image. It may be that the ext directory is empty by
default (localdata.jar and cldrdata.jar will not exist). "

"GensrcCLDR.gmk and GensrcLocaleDataMetaInfo.gmk generate sources for
java.base and jdk.localedata. I think we should re-examine to modify
the tool e.g. to take an input parameter specifying which locales or
module the source is generated for. This will make the i18 build
better fit the new modular build logic such that Gensrc-java.base.gmk
generates the source for java.base and a new Gensrc-jdk.localedata.gmk
generates the source for jdk.localedata."