Added a option to use the OS native share modal.

[DhrRob]

Add a native share modal navigator.share().
Would probably have to add some check (e.g. is_ssl()) to check if HTTPS is being used, as that's a requirement for the Navigator.share().

In reference to:

1. Include default share sheet button #19
2. add web share api button #24

My first ever PR, hope this is alright!

[DhrRob]

Tried creating a new social-sharing-block.pot but ran into errors sadly.

 *  Executing task: npm run update-pot 


> [email protected] update-pot
> wp i18n make-pot . languages/social-sharing-block.pot --exclude=src

'wp' is not recognized as an internal or external command,
operable program or batch file.

 *  The terminal process "C:\Program Files\PowerShell\7\pwsh.exe -Command npm run update-pot" terminated with exit code: 1.