Rewrite chat input and inline commands to ChatGPT-like style

**Is your feature request related to a problem? Please describe.**
The current command implementations cause a lot of bugs: #2326, #2264, #1890, #2032, #2087

**Describe the solution you'd like**
The input should be responsible only for handling user input (i.e. text) and should not interfere with any additional functionality.
