Adding 'bets#show' content

This PR adds content for the 'bets#show' view page.

This PR does NOT address styling of the page. That will be separate.

cc @Clee681 @irmiller22 LMK what you think please
@Clee681 @irmiller22 This doesn't feel very DRY, having both of these methods with **extremely** similar names.

As a general note, I have been noticing this happening a LOT at various places in the code. As in, I do the following:

1. Check the relationship between `current_user` and the `bet` (i.e. is `current_user` the inviter or invitee?)
1. Write two methods, one to cover each potential relationship that displays the attribute I'm working on at the time
1. Use those helpers from #2 to selectively display either the `invitee_amount` or `inviter_amount` based on the result of #1