mcp server：support base-url

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Expected Behavior

@see https://docs.spring.io/spring-ai/reference/api/mcp/mcp-server-boot-starter-docs.html#_configuration_properties

base-url
Optional URL prefix. For example base-url=/api/v1 means that the client should access the sse endpont at /api/v1 + sse-endpoint and the message endpoint is /api/v1 + sse-message-endpoint

Current Behavior

config base-url is not support for sseEndpoint, messageEndpoint prefix

Context

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PR：#195
cc： @tzolov thank you.

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related spring-ai PR: spring-projects/spring-ai#2724