Fix token selection dropdown

[mds1]

Closes #6867

Changes:

• Replaces select2 component :options parameter with <option> elements
• Replaces underscores with emdashes for token divider (this centers the divider in its row instead of having it at the bottom)

To test:

1. Add multiple grants to cart
2. Remove one
3. Make sure token selections do not change
4. Change token selections of remaining grant check local storage > grants_cart
   and make sure the grant_donation_currency field is updated and matches what is in the token selection box

cc @owocki @apbendi