Added option for connection timeout used when browser extension is trying to connect to KeePassXC

[Talkabout]

This small feature adds a connection timeout setting which is used when keepassxc-browser extension is trying to connect to KeePassXC instance.

Fixes https://github.com/keepassxreboot/keepassxc-browser/issues/2751

Screenshots or videos

Testing strategy

I tested this feature by making sure that:

• default value (1.5) is considered, if no other value has been set
• changed value (10) is used when assigned in extension options

Type of change

• ✅ New feature (change that adds functionality)

[droidmonkey]

I recommend a slide bar that varies between 1.5 seconds and 60 seconds vice a text input.