[DISCUSS] KAFKA-5669: Define allowed characters for connector names

[Sönke Liebau <so...@opencore.com.INVALID>]

As stated in the jira, we should come up with either a set of allowed or a
set of disallowed characters  for connector names to avoid a couple of
issues that currently exist.

I tend towards a whitelisting approach to avoid missing a lot of things
that then need to be fixed later on.

According to RFC 3986 the set of allowed characters for a path element in a
URI is:

a-z A-Z 0-9 . - _ ~ ! $ & ' ( ) * + , ; = : @

So my initial suggestion as basis for discussion would be to go with these
and test whether any of those create issues - then we can see whether its
worth fixing the issues, or easier to just blacklist the characters.