fix(connections): a URI connection saved without a name is named after the form's default host, not the URI #1257

Problem

When a connection is created from a URI and the name field is left empty, each form names it differently, and Redis and MongoDB name it after the host field (default localhost), not the host in the URI.

The Redis and MongoDB names point at a server the connection does not use. With several URI connections, the sidebar shows identical names (Redis localhost:6379 for every one). MySQL's name is not wrong, but it tells nothing about the server.

Found while writing the connection-form e2e scenarios (#1050, #1256). Those tests check the URI in the secure store and do not assert the name, so they do not pin the current behaviour.

Scope

• One rule for all four forms: with an empty name and a URI, the name is <Type>: <uri host>:<uri port> (port = the URI's or the type's default), as PostgreSQL does now.
• Fall back to <Type> (URI) only when the URI has no host (e.g. a Mongo +srv URI without one, a malformed URI).
• A shared helper for the URI host/port, instead of one per form.

Acceptance Criteria

• MySQL, Redis and MongoDB name a URI connection after the URI's host and port.
• Widget tests per form: URI typed, name empty → expected name.
• The e2e form scenarios (test/e2e/01_connection_lifecycle/e2e_connection_form_test.dart) assert the name contains the URI's host.