Change chars for `MultiSelect` items

[Gordon01]

Windows Terminal, a widely used terminal emulator for some reason does not support coloring for '✔' char. '✔️' and '❌' may be used instead. They work down to the previous Windows terminal emulator: conhost.exe.

Before:

Windows Terminal

As you can see, selected and unselected items are indistinguishable.

conhost.exe

Surprisingly, the old windows emulator is better than new one.

VSCode

After:

Windows Terminal

conhost.exe

VSCode

[Gordon01]

This fixes https://github.com/console-rs/dialoguer/issues/202 with a well-supported character down to early windows-style utf-16ish.

The theme looks good and is consistent on different emulators.

Additional testing is needed for: https://github.com/console-rs/dialoguer/issues/149

[pksunkara]

IMHO, it doesn't look good.

[Gordon01]

Which new rendering do you think is the worst?

The new VSCode's terminal rendering is questionable.

[pksunkara]

The same rendering is also used for Mac and Linux, where the X emoji does not look good.

[Gordon01]

What about '☑' '☒' or '✔' '✘' '☓'

[Gordon01]

'◌' looks good. I removed the color because some emulators drew it black which is invisible on the default black background. Here are a few screenshots.

windows term:

conhost:

vscode:

black is invisible both in windows term and in conhost.exe:

[Gordon01]

Linting fails because of: https://github.com/console-rs/dialoguer/pull/209

[pksunkara]

Feel free to fix it in this PR

[Gordon01]

Linting and changelog fixed.

[Gordon01]