Add Special Causes Donation Option on Main Site

[mekkim]

We've been raising money specifically for CO2 monitors for school teachers across Canada and some folks have suggested we add a feature that allowed them to specifically donate for that cause on the main donation site. For Paypal, there's a simple way to do that, but I'm not clear on the easiest way to add something like "Dedicate this money to CO2 monitors for Teachers fund".

Perhaps the easiest way would be to just add a notes field to all donations that's only visible to us that can be populated by a pull list on the page whose contents we can change depending on programs in progress. Default list could look like the Paypal one:

1. Towards DonateMask.ca Free N95-equiv Masks & Rapid Tests
2. Towards any EBSECan program / General Fund
3. Towards Community Cats Canada (later will be its own page so maybe not included here)
4. Towards CO2 Monitors for Teachers

[HaiderZaidiDev]

I'm thinking we can add a dropdown menu with these options, then just update the meta data when posting this to Stripe and the database. Then when we're checking the donations we can see their preference for how it's allocated - will start working on this