Bugs related to hotkeys involving the enter key

**Describe the bug**
If you set `` for a label, the label is selected also by pressing only alphanumeric characters without pressing the enter key. For example, if the hotkey for a label is `enter+a`, the label is selected also by pressing only the `a` key.
And if the label is set as ``, all the labels set in the same way are selected by pressing only the enter key. For example, if the hotkey for label 1 is `a+enter` and the hotkey for label 2 is `b+enter`, then labels 1 and 2 are selected by just pressing the enter key.

**Environment**
- OS: macOS Monterey
- Label Studio Version: 1.4.1