Update the Teleport and Escape Rod common events' behavior

[pw-rey]

PR Description

As reported in this help topic on Discord, the Technical Demo doesn't reset the player's state when using Teleport, the Escape Rod and Dig which uses the Escape Rod's behavior. This PR solves this issue.

Before testing

• Make a Pokémon of yours learn Teleport: S.MI.skill_learn($actors[0], :teleport)
• Give yourself some Escape Ropes: $bag.add_item(:escape_rope, 10)
• If you're using an existing save, make sure to walk in and out of the Tower once or twice to ensure the new return coordinates variables will be properly saved

Tests to realize before merging

• For all of the tests below, make sure to test the $game_player.z command in the console. If it returns anything other than 1, then the test case is invalid
• Go to the River map and walk to the middle of the bridge, then use both an Escape Rope and Teleport with your Pokémon: you should appear below the Tower's door and you should be able to walk with no issue
• Go to the March map, walk into the swamp, then use both an Escape Rope and Teleport with your Pokémon: you should appear below the Tower's door and you should be able to walk with no issue
• Go to the Bike map, step onto your own bike, then use both an Escape Rope and Teleport with your Pokémon: you should appear below the Tower's door and you should be able to walk with no issue