Create invoice page

[lanaramadan]

Description

Created InvoiceTitle, InvoiceStats (which includes payees), InvoicePayments components for the single Invoice page. Also added pagination.

Screenshots/Media

Issues

Closes #53

[lanaramadan]

One thing we weren't confident with is the "Remaining Balance" section.

Since it depends on the total and paid values of each invoice we had 3 options:

1. Somehow call invoices/total/:id and invoices/paid/:id inside /events/remainder/:id — this only seemed feasible if we used axios.get, which we weren’t sure what endpoint to use then (also, apparently this isn’t really recommended online for some reason) and the endpoints weren't actually fully implemented (nor did we know how to implement them since it's unclear where those values would be derived from).
2. Reusing the code in invoices/total/:id and /invoices/paid/:id in a third endpoint. But the endpoints aren’t fully implemented and it would've led to bad modularity.
3. Use JS to calculate the remaining balance.

We went with the third option, but let us know if we should change anything (and how).

[theNatePi]

Good work guys! Some edits:

• Some invoices show no data, such as invoice with ID = 4
• The "Program:" title at the top seems to be showing the description of the program, when it should show the name of the program
• The "Billed To" Section should only show the payees, not the instructor
• I think you left some console.log's in there, make sure to remove them
• In the invoice page, you call await backend.get("invoices/" + id); twice. Make sure to only do this once and to re-use the first content
• It seems that the indent spacing in events.js (the router) went from 2 spaces to 4. Make sure all tab spacing is 2 spaces
• The invoices router might also have some new indent spacing issues, make sure it is also consistant

Don't worry about changing the remaining balance implementation you have

Important

Make sure to pull before making modifications
Reminder: These fixes are due Tmr at midnight

Very good work on the table, it works really well!
@lanaramadan @AstonKiChan

[lanaramadan]

Nonexistent invoices:

Invoices with missing fields:

Invoices with no issues:

[brelieu05]

my bad, accidentally changed the label thinking it was my PR

[theNatePi]

LGTM!