Add --connection-string parameter ABP CLI while creating a new project

[ebicoglu]

Users can be able to set a database connection string while creating a new project via ABP CLI. Because the current connection string is not in one place and needs to find/replace to change in various places.

Usage should be:
abp new Acme.MyProject --connection-string <my-custom-connection-string>

[maliming]

We should remind developers in the cli that the connection string can only be sql server.

[hikalkan]

@ebicoglu we should write this to the document. something like that:

conn string can only be sql server since the default provide is sql server. if you will use another dbms, then see this document.