Add preference page for the stack frames grouping feature

[gzsombor]

What it does

Adds a preference page for the stack frame grouping feature - this is a stripped down version of #81

How to test

Open Window -> Preferences -> Java -> Debug -> Stack Frames and change the values push button etc

Author checklist

• I have thoroughly tested my changes
• The change is following the coding conventions
• I have signed the Eclipse Contributor Agreement (ECA)

[stephan-herrmann]

FYI, warnings should vanish once you rebase (to benefit from #802).

[gzsombor]

@iloveeclipse could you please have a look on it?

[iloveeclipse]

could you please have a look on it?

I'm sorry, too busy with other tasks. It's on my list for tomorrow.

[iloveeclipse]

Sorry, I probably was not clear here: I only asked for the preference page for the "Collapse stack frames", and the rest with the new highlighting feature in a different PR.

What I see is the preference page for everything, even for features that are not yet there:

I would be happy to merge the preference page change if the only would allow to configure available "Collapse stack frames" feature. Could you please make it, or should I change the PR to cover only that feature?