[Bracket Builder] Improve UX for adding matches in round (i.e. with different placement types)

[resir014]

Description

Currently we cannot set matches in a round with multiple spot types (i.e. changing this option will reset everything).

This was a shortsighted UX decision in the past that's been a nuisance ever since. We never took into account there was cases where a round/match can have multiple spot types. (e.g. for invited slots)

Implementation Model

Mainly UX improvements are needed for adding rounds, matches, and spots. See official comp tool for inspiration?

Tasks

• [infra] Migrate from yarn v1 to pnpm #42
• [BB] Changing placement type in a round clears the entire round #39
• [BB] Add spot types for specific team names #40
• Improve create round/match UX (allow multiple spot types in a single match)
• [UI] Add tooltips for buttons without labels #45