http-client-java, support exact in clientName (#10758)

fix https://github.com/Azure/autorest.java/issues/3340

manual tested on
https://github.com/Azure/typespec-azure/blob/main/packages/azure-http-specs/specs/azure/client-generator-core/exact-name/main.tsp
need its release to write e2e

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Impl is relatively simple. If `isExactName`, set the name directly to
`language.java.name`. And later in Java code this name will not get
transformed (otherwise, Java code will do a transform from
`language.default.name` to `language.java.name`).

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It is not complete though. There is `isExactName` missing from some
types. TCGC fixed but not released.
https://github.com/Azure/typespec-azure/pull/4480

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