[FR]: Allow manually typing paths of external tools

[guihkx]

Brief description of the feature request

I wish I had the option to add an external tool (in Settings > Network & web & tools > External tools), by manually typing the path of the binary, instead of having to choose one from the file chooser dialog.

This is already possible when setting a Custom external web browser, for example:

Video_2024-03-26_11-15-43.mp4

Nice to have:

• Allow setting an alias for each external tool added
• Allow suppressing stdout / stderr messages from the spawned process (e.g., mpv is very noisy by default)

Thank you very much!