RFR: 8345139: Fix bugs and inconsistencies in the Provider services map [v2]

[Francisco Ferrari Bihurriet]

> Hi, this pull request implements the fixes for bugs and inconsistencies described in [JDK-8345139](https://bugs.openjdk.org/browse/JDK-8345139 "Fix bugs and inconsistencies in the Provider services map").
> 
> #### New services map design
> 
> Here is the high-level hierarchy of the new services map design:
> 
> * `servicesMap` (`ServicesMap`)
>     * Instances
>         * `impl` (`ServicesMapImpl`)
>             * `services` (`Map<ServiceKey, Service>`): unifies the previous `serviceMap` and `legacyMap`
>             * `legacySvcKeys` (`Set<ServiceKey>`): set indicating which keys in `services` correspond to the Legacy API
>             * `serviceProps` (`Map<ServiceKey, String>`): keeps track of the _provider Hashtable entries_ that originated services entries <sup>(1)</sup>
>             * `serviceAttrProps` (`Map<ServiceKey, Map<UString, String>>`): keeps track of the _provider Hashtable entries_ that originated service attributes <sup>(1)</sup>
>         * `serviceSet` (`AtomicReference<Set<Service>>`): part of a lock-free mechanism to implement a consistent version of the `getServices()` readers method
>     * Writers' methods (for providers registration)
>         * `Current asCurrent()`: returns `impl` seen as a `Current` interface implementer
>             * `putService(Service svc)`
>             * `removeService(Service svc)`
>         * `Legacy asLegacy()`: returns `impl` seen as a `Legacy` interface implementer
>             * `putClassName(ServiceKey key, String className, String propKey)`
>             * `putAlias(ServiceKey key, ServiceKey aliasKey, String propKey)`
>             * `putAttribute(ServiceKey key, String attrName, String attrValue, String propKey)`
>             * `remove(ServiceKey key, String className)`
>             * `removeAlias(ServiceKey key, ServiceKey aliasKey)`
>             * `removeAttribute(ServiceKey key, String attrName, String attrValue)`
>     * Readers' methods (for services users and `GetInstance` APIs)
>         * `Set<Service> getServices()`
>         * `Service getService(ServiceKey key)`
>     * Other methods: default and copy constructors, `void clear()`
> 
> (1): to maintain the consistency between the provider's `servicesMap` and its _Hashtable entries_, even if Legacy API updates occur through _properties_ with different casing, or aliases instead of main algorithms.
> 
> #### Testing
> 
> As part of our testing, we observed all the tests pass in the following categories:
> 
> * `jdk:tier1` (see [GitHub Actions run](https://github.com/franferrax/jdk/actions/runs/1219321...

Francisco Ferrari Bihurriet has updated the pull request incrementally with one additional commit since the last revision:

  Copyright update.
  
  Co-authored-by: Martin Balao Alonso <mbalao at redhat.com>
  Co-authored-by: Francisco Ferrari Bihurriet <fferrari at redhat.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/22613/files
  - new: https://git.openjdk.org/jdk/pull/22613/files/95364f86..bda8971f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22613&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22613&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/22613.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22613/head:pull/22613

PR: https://git.openjdk.org/jdk/pull/22613