Consider supporting request-level database protocol and database metadata mock

## Feature Request

### Is your feature request related to a problem?

No.

### Describe the feature you would like.

At present, the master branch of ShardingSphere can only support a specific database protocol after startup, such as MySQL protocol or PostgreSQL protocol, and then mock different database metadata according to the database protocol type.

This usage is not flexible enough, and users cannot dynamically switch database protocols and database metadata. So we hope to support request-level database protocols and database metadata by listening to different ports. Then according to the type of the request protocol to mock database metadata.

No files or tests are named. Start by mapping where the startup-selected database protocol and mocked metadata are configured, then trace request handling and port selection. Done means requests on different ports can select their protocols and corresponding metadata without restarting.

Written by the indexing model from the issue text.