Add urlencode support to [current-page:title] token

This is actually useful within Token and it's not only related with Social Media issue.
I'm using it with TextImage and this patch works as it should.
Only 2 issues:
- the "titleencode" token doesn't appear in the available tokens
- the naming could be improved matching the other patterns, something like "title:encoded"

Prashant.c → made their first commit to this issue’s fork.

I swapped title:encoded for title-encoded and added the token info.
The resulting token is [current-page:title-encoded], but I was wondering if it's any better provide it as utility in order to encode any token, eg [any-string-token:encoded].
Any thoughts from the maintainers?

To have nested tokens, they need a type, and traversing to children needs to be explicitly supported and implemented for every single token, so any-string-token:encoded is not feasible with the current token system.

I'm not convinced this is needed. It's IMHO up to the logic calling token replace to apply appropriate encoding on any value that's been replaced by the token. You might want to have a look at how metatag for example handles that.