[sv-ec] Covergroup option assignment - Mantis #1240

Attached is a proposal for Mantis 1240.

The proposal only allows assignment of the 'auto_bin_max' and
'detect_overlap'
options in a covergroup or coverpoint declaration. IE. These options
cannot be dynanically assigned after the covergroup instance is created.

In the previous SV-EC meeting, it was AGREED that these options are
applied at the time the instance is created and that dynamic assignment
of these options (after the instance is created) would NOT change the
instance.

There was discussion that it was desirable to dynamically assign these
options and then expect that the new values would apply to any
subsequently created instance of the covergroup. The assumption in the
meeting was that these are TYPE options. However, these are per-instance
options. Therefore, dynamic assignment of these options (that doesn't
change the instance) is only confusing / misleading. Thus this proposal
only allows assignment in the declaration.

- Ray