[Survey Accounts] Batch send surveys

[miladheshmati]

Brief summary of changes

This PR changes the instrument select in the "add survey" section to a multi-select

• [x] Have you updated related documentation?

Testing instructions (if applicable)

1. Go to Survey Accounts
2. Click on Add survey
3. The instrument selection should be a multi-select

Link(s) to related issue(s)

• Resolves #8984

[driusan]

@miladheshmati The tests on this are failing

[miladheshmati]

@miladheshmati The tests on this are failing

@driusan I think it is related to the element change that we had to do in this PR. Should we modify the tests?

[driusan]

@miladheshmati Yes, if required.

[driusan]

@miladheshmati The tests on this are still failing and there's a file conflict in addsurvey.class.inc