Core: Replace item link locations with modified collect/remove

[Mysteryem]

What is this fixing or adding?

This patch removes the locations from item links, fixing a couple of issues with item links:

1. By removing the locations, there are no longer any concerns about unreachable item link locations failing location accessibility requirements.
2. Because the linked items are no longer placed at locations and are collected with the group unlocker items simultaneously, additional spheres are no longer required to pick up the linked items.

However, there are some downsides:

1. In a spoiler, it is no longer immediately clear which players have an item locked behind a group unlocker item.
   • This has been resolved by changing the conversion to a string representation for group items/locations to also include the names of the players that belong to the group.
2. In a spoiler playthrough, it is no longer clear which of the linked items unlocked by collecting a group unlocker item are required to beat the game. Previously, each linked item would be placed and locked at a unique location, so only each individual linked item that was required to beat the game would be present in the spoiler playthrough. With this patch, if a group unlocker item unlocks linked items for 10 players, but only 1 of those linked items is needed to beat the game, there is no way to tell that this is the case because only the group unlocker item will show in the playthrough.
3. Because the linked items are no longer placed at locations, they will not be found by worlds that use multiworld.get_spheres() or similar.

How was this tested?

I generated seeds with Bumper Stickers with Everything item linked, as well as A Hat in Time with linked Time Pieces, Hookshot Badge and Scooter Badge.

If this makes graphical changes, please attach screenshots.

In a spoiler, a location/item belonging to a group will now also write the names of the players within that group:

Treasure Bumper 28 (Player5): 100 Pons (Player3)
Treasure Bumper 29 (Player5): Treasure Bumper (link_test (Player8, Player5, Player6, Player7))
Treasure Bumper 30 (Player5): Yarn (Player2)