v6: Authorization and connection helpers

[bevzzz]

API Key authorization

In this PR we introduce a TokenProvider interface, which is a popular abstraction for dealing with access tokens. io.weaviate.client6 exports Authorization util class with factory methods to setup (various kinds of, in the future) token providers.

For example, Authorization.apiKey("my-api-key") creates a TokenProvider for a static Weaviate API key.

Connection helpers

// Local Weaviate instance with default parameters:
// scheme=http, host=localhost, httpPort=8080, grpcPort=50051
var local = WeaviateClient.local();
var localAsync = WeaviateClientAsync.local();

// Weaviate Cloud instance with default parameters:
// scheme=https, httpPort=443, grpcPort=443
var wcd = WeaviateClient.wcd("my-cluster.wcd.com", "token-xyz");
var wcdAsync = WeaviateClientAsync.wcd("my-cluster.wcd.com", "token-xyz");

When connecting to a Weaviate Cloud instance, gRPC host is inferred: "grpc-" + httpHost, similarly to Python's client.

// Custom configuration
var custom = new WeaviateClient(Config.of(
  "https", cfg -> cfg
    .httpHost("my-http-host.com")
    .grpcHost("my-grpc-host.com")
    .authorization(Authorization.apiKey("token-123"))
    .setHeader("X-Custom-Header", "abc+def")
));

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   1   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Failed	Vulnerabilities	1   0   0   0	View in Orca

🛡️ The following SAST misconfigurations have been detected

	NAME	FILE
	Insecure Random Number Generator Usage in Java	.../ConcurrentTest.java	View in code

☢️ The following Vulnerabilities (CVEs) have been detected

	PACKAGE	FILE	CVE ID	INSTALLED VERSION	FIXED VERSION
	org.apache.httpcomponents.client5:httpclient5	./pom.xml	CVE-2025-27820	5.4.2	5.4.3	View in code

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Secrets	0   0   0   0	View in Orca