feat(xds): named resources (clusters) builders require name

[mmorel-35]

Defines the cluster name as a required field for the builder constructor function and adds a validation in the final build function to throw an error if the field is blank.
It also removes the name assignation from several configurers. It asserts that the name shall be known when the builder is instantiated.

Checklist prior to review

• Link to relevant issue as well as docs and UI issues -- xDS generators should require resource names #2538
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as a image registry) and it will work on Windows, system specific functions like syscall.Mkfifo have equivalent implementation on the other OS --
• Tests (Unit test, E2E tests, manual test on universal and k8s) --
• Do you need to update UPGRADE.md? --
• Does it need to be backported according to the backporting policy? --
• Do you need to explicitly set a > Changelog: entry here or add a ci/ label to run fewer/more tests?