tiny_tds v4

[andyundso]

It's only been a short time since the last major release (see #552). That one mostly focused on removing things that were EOL for a while (e.g. old SQL or Ruby versions). Howver, I see potential for a v4 to further modernize the code base.

This likely needs a separate branch so we can keep releasing bugfixes / version updates for the libraries from main.

Refactor tiny_tds to avoid sharing DBPROCESS
There is already PR for this (#571), which also gives more details about the why's and how's.

Support keyword arguments instead of options hash
Support modern Ruby syntax.

Bump the TDS version to v7.4
with v3, support for anything older than SQL server 2017 has been dropped already. TDS v7.4 is understood by SQL server 2014 and above, so I think we are safe to bump the default TDS version to v7.4, as well as removing support for anything older.

This would also enable to implement #184 without any extra checks in C.

Separate new and connect
There is also already an issue for this (#570). As explained, it would allow us to easier hand-off the GVL in order to resolve #421.

Bump minimum Ruby version to 3.2