Add context menu items to Code Explorer to set VB attributes

[mansellan]

Justification
Make it easy to set VB attributes directly from the Code Explorer.

Description
In the vanilla VBE, it's irksome to set attributes. (Some of the?) module-level attributes can be set from the properties window. For procedure attributes, VB6 has a dialog available, but the UX is extremely poor, and for VBA there is no UI at all - procedure attributes can only be set by exporting the module, adding the attibutes as text and reimporting.

Rubberduck currently helps by automating this process with annotations (and for predeclared modules, a template). However, we can make it easier still by adding context menu items in the Code Explorer that can set these attributes (backed up with RD annotations) with a click or two.

Related: #4876

[retailcoder]

Seems a duplicate of #4790?

[mansellan]

Certainly related, but #4790 approaches from annotations, this approaches from attributes. Happy to merge them?

[bclothier]

Linking #4227