Allow features to take ownership of the workspace and deny external changes

[dpoeschl]

Specific instances where we want to suppress the lightbulb (and probably other workspace features):

• Inline Rename
• Debugging (but not broken into)

[shyamnamboodiripad]

This issue specifically mentions rename. However, the workspace ownership is a general problem in other scenarios too. For example, when a debug session is active but code is not at a breakpoint we have similar problem where light bulb offers fixes - but fixes silently fail because workspace refuses to apply the changes in this mode. If we had a mechanism to track workspace ownership, then we could just hide the light bulb in such cases / at least avoid failing silently (we could say that debugger owns the workspace and hence a fix can't modify it).

It would be good to add such mechanism to track workspace ownership (light bulb would be one consumer of this mechanism - but there could be others too).

[dpoeschl]

@shyamnamboodiripad I've changed the title and description (the 1st comment in the issue). Please feel free to update either/both of these so that the current state of the issue is properly reflected.

[shyamnamboodiripad]

Thank you @dpoeschl