Remove connection string parser

[dhensby]

What this does:

v7 stopped using our built-in connection string parser in favour of @tediousjs/connection-string, the code was left in pace for users that still wanted to use it themselves.

It is now removed and developers who want to parse connection strings can now use parseConnectionString function that is statically available on ConnectionPool.

This officially removes any kind of support for URI style connection strings until it is added to the tedious package.

Pre/Post merge checklist:

• Update change log