tea.ExecProcess does not restore mouse motion

**Describe the bug**
Run vim with tea.ExecProcess, exit vim -> no mouse events, also some problems with altscreen.

**Setup**
Please complete the following information along with version numbers, if applicable.
- OS macOS
- Shell zsh
- Terminal Emulator Terminal.app
- Terminal Multiplexer none

**To Reproduce**
Steps to reproduce the behavior:
1. Use https://fx.wtf
2. Click on 'v' to open file.
3. Exit vim.
4. See error

**Source Code**
https://fx.wtf

**Expected behavior**
AltScreen and MoueCell restored.

Start at the tea.ExecProcess entry point and reproduce the problem using the fx.wtf application: open a file with vim, exit it, and check mouse events and the alternate screen state. Trace the terminal-state cleanup and verify that mouse input and AltScreen are restored after the process exits.

Written by the indexing model from the issue text.