Search by Campaign(s) for component search and advanced search component panes

When CiviCampaign is enabled add a "Campaigns" filter to the following search forms. The filter needs to support multi-select - I would recommend using the crmasmSelect widget for input. I think current campaigns should be easier to select, so perhaps divide the drop-down into "Current Campaigns" and "Past Campaigns" (where current includes anything with end date <= now).

1. Component searches:

• Find Activities
• Find Contributions
• Find Memberships
• Find Participants
• Find Pledges

The filter for the above should be available in the corresponding Advanced Search panes.

2. Other searches

• Find Mailings
• Manage Contribution Pages
• Manage Events