Support SteppingGranularity "block"

[corneliusweig]

DAP supports SteppingGranularity, which is defined as

type SteppingGranularity = 'statement' | 'line' | 'instruction';

However, some debuggers like LLDB support stepping to the end of a block. From LLDB help:

$ help thread step-over
       -e <linenum> ( --end-linenumber <linenum> )
            The line at which to stop stepping - defaults to the next line and only supported for step-in and step-over.  You can also pass the string
            'block' to step to the end of the current block.  This is particularly use  in conjunction with --step-target to step through a complex
            calling sequence.

So the following steps to the end of the current block:

thread step-over -e block

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Could this "block" verb be added to SteppingGranularity?