Refactor the handling of JSR-330, JSR-250 and Jakarta annotations in `ServiceProvider`

[desruisseaux]

Changes in this merge request:

• Allows javax.inject and jakarta.inject to coexist on the classpath. Before this commit, if both were present on the classpath, then the code checked only javax.inject annotations and Jakarta was ignored.
• If both annotations are present on the same class, give precedence to Jakarta. In my understanding, javax.inject annotations are deprecated in favour of jakarta.inject. See for example OpenRewrite.
• Added the use of Jakarta @Named annotation in JUnit test, for testing the code path that check annotation values.
• Minor bug fix in the if (name != null) check: after the addition of Jakarta annotations, a pair of { … } should have been added for applying the condition to both JSR and Jakarta annotations. Before this commit, the condition applied only to JSR annotations because of missing { … }. The bug was there:

https://github.com/unitsofmeasurement/unit-api/blob/b5ca1576b7df480d7692ea26bbfd9c332945b5c0/src/main/java/javax/measure/spi/ServiceProvider.java#L183

After above changes are applied, the second commit specializes the Java 9 implementation for taking advantage of Java 9 capability to defer the initialization of ServiceProvider implementations. The deferred initialization is handled by ServiceLoader.Provider (new in Java 9).

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This change is 

[desruisseaux]

Fixed one of the two "Codacy" complains (about field declarations on separated lines). The second complain (about reassigning parameters) should be ignored. Following Codacy advice would just make the code more complicated for no good reason. I think that I do not have the authorization to bypass Codacy myself.