Add hitcount column to Breakpoints view

Currently the user can configure a "Hit count" value as Breakpoint condition:

But the user can not see how often the breakpoint did already hit.

Together with a resume functionality (https://github.com/eclipse-jdt/eclipse.jdt.debug/issues/614) or condition=false the actual hitcount could also be used as poor mans invocation counter. "Poor man" because probably a simple implementation would be to slow to measure millions of hits. But we could give it a try and even for few Hitcounts the information may be worthy.


- The column may be optional and configurable if its shown.
- One might want to sort by that column value
- It might be useful to add a "Toggle Hitcounter" in the contextmenu

WDYT?