Unicode paste support

[yurivict]

Describe the bug
The "→" character isn't pasted.

To Reproduce
In the Web interface:

1. Click Text
2. Paste "→", which is a UNICODE character
3. Click Paste
4. Nothing happens - this character isn't pasted into the remote computer

When the text x→y is pasted from the web interface - only "xy" ends up to be pasted.

Expected behavior
n/a

Desktop (please complete the following information):

• OS: FreeBSD 14.0
• Browser chrome

PiKVM info:

• Raspberry Pi board version RPi 4
• PiKVM platform v2-hdmi
• Video capture type CSI bridge
• KVMD version: 3.284-1
• uStreamer version: 5.45-1
• Linux kernel: 6.1.61-1-rpi-ARCH

[mdevaev]

We can only insert characters that are on the keyboard. PiKVM has no connection to the OS, so the paste function uses typing on a virtual keyboard. Alas, it cannot be done otherwise.

[yurivict]

But there is (almost) always a way in modern systems to enter UNICODE characters when the system is fully booted into a graphical environment.

In Linux/*BSD in a graphical environment: Ctrl+Shift+u-{HHHH}-Enter.
In Windows: {HHHH}-Alt+X.
In MacOS: Hold the "option" key - enter {HHHH} - release the "option" key.

PiKVM could offer the user an option to choose how to enter UNICODE characters.
This could be a possible improvement in how the text pasting function works.
"None" could be one of the choices, in which case it would enter question marks in place of UNICODE characters.

[mdevaev]

Actually it makes sense. I'll add it to plan.