refactor(angularjs): remove angular-moment

[LoneRifle]

Problem

As we prepare for the React migration, we should minimise the number of
AngularJS-specific libraries that are currently in use.

Solution

As we have no need for the AngularJS filters and directives that
angular-moment provides, remove it completely, referencing moment
as a CommonJS module instead.

Testing

Verify that date formatting remains correct for:

• Admin dashboard form list
• Form builder heading
• Viewing responses in storage mode
• On form submission

[mantariksh]

@LoneRifle could you explain more about this? I’m actually not sure this is helpful for React migration because it doesn’t give us any code which we can battle-test in production and then reuse in React. regardless of whether we use moment-timezone or angular-moment in AngularJS, we're going to throw out the code anyway.

[LoneRifle]

@LoneRifle could you explain more about this? I’m actually not sure this is helpful for React migration because it doesn’t give us any code which we can battle-test in production and then reuse in React. regardless of whether we use moment-timezone or angular-moment in AngularJS, we're going to throw out the code anyway.

I agree - however, I think that we ought to throw out code earlier if we think we can, so that there is less to figure out later on. This PR would also help to better identify dependencies on moment-timezone within components so that moving these out of AngularJS would be easier.

[mantariksh]

This PR would also help to better identify dependencies on moment-timezone within components so that moving these out of AngularJS would be easier.

ok! agree here

[mantariksh]

Manual tests

• Modify a form and check that the "last modified" under the form title in the admin dashboard is formatted the same way as in production
• Check that the "last modified" date for forms in the form dashboard is formatted the same way as in production
• Storage mode CSV download works correctly
• Formatting of submission date in end page (page after submitting form) works correctly