Before this change MvcUriComponentsBuilder exposed only static factory
methods for creating links where the links are relative to the current
request or a baseUrl explicitly provided as an argument.
This change allows creating an MvcUriComponents builder instance with
a built-in baseUrl. The instance can then be used with non-static
withXxx(...) method alternatives to the static fromXxx(...) methods.
Issue: SPR-12617
1cd0f433e0