Create a util to more concisely parse query params

[regarding v6]

Currently, there are two issues with the way we are parsing query params:

1. Users need to pass `=true` to query params for them to take hold, i.e. `localhost:3000/?presenterMode=true`
2. Location matters, so a user cannot append their URL with `presenterMode=true`, it has to come immediately after the localhost, before any other `slideElements` are tacked on

We should handle this differently. In addition to parsing these in a cleaner way, we should add support for (listed in priority order):

- `?presenter`
- `?overview`
- `?export`
- `?print`
- `?export&print`