feat: provide completion for Resource Bundle keys

[fbricon]

Fixes #881

• provide completion for keys in resource bundles
• controled by the "java.completion.resourceBundle.enabled" preference, enabled by default.

Known limitations:

• only checks for bundles in the project, not bundles embedded in jars on the classpath or modulepath
• doesn't provide completion for bundle names (doable but would require scanning the whole source tree). Maybe later

Opens the door to more potential enhancements

• key validation
• navigation to bundle
• hover on keys showing value

Signed-off-by: Fred Bricon fbricon@gmail.com

[datho7561]

Works pretty good!

Completions are still suggested at the second argument, eg.

bundle.getString("my.first.translation", /* here */);

Annoying but not a deal breaker IMO.

If I hardcode a locale, the completion details still show the value from the bundle without the locale. I guess this behaviour makes sense, since the locale is usually dynamic instead of hardcoded.

[fbricon]

Adding support to the locale, I had to throw away a lot of code to change my approach. I'm getting there.