Tweak "cannot classify" wording for Project Manager

[tomdoel]

If a Project Manager clicks Classification for a Work Package, they see the message You cannot classify this work package as you have not been assigned to it. Please add yourself to the work package with a relevant role if you need to go through the classification process.

There are a couple of issues with this:

• The Project Manager will see the message even if they are already assigned to the Work Package (as PM role), so the first part of the message is confusing. It may be worth adding a specific message for this scenario as it will be very common for project managers to look at the classifications in progress.
• Regarding the second part of the message, I'm not sure that a PM can assign themselves a classification role to a work package (except by being a Data Provider Representative) because WP roles are inherited - to be an Investigator or Referee they would have to change their role on the project and thus lose their Project Manager status - @steven-cd is this correct?

[steven-cd]

Hmm, you're right - I think that message was written more with the assumption it would be Programme Managers who saw it, who could then assign themselves an appropriate role if necessary. Project Managers definitely can't, at least not without losing their Project Manager privileges. I think in practice though, there are probably very few times where it would be appropriate for either of these roles to actually go through the classification process, so maybe it is best to just change the message to say You cannot classify this work package as you do not have the appropriate role., without any further explanation

[tomdoel]

@steven-cd that would be the simplest change - @bw-faststream do you agree?

[bw-faststream]

I agree, this should fix it well enough

[tomdoel]

Fixed in #315