Extract caching logic into a separate gradle-actions-caching component (#885)

With this change, the caching functionality of `setup-gradle` and
`dependency-submission` is now provided by `gradle-actions-caching`, a
closed-source library distributed under our [Terms of
Use](https://gradle.com/legal/terms-of-use/). The rest of the action
implementation remains open source.

Using `setup-gradle` or `dependency-submission` with caching enabled
involves loading and using the `gradle-actions-caching` component,
requiring acceptance of the [Terms of
Use](https://gradle.com/legal/terms-of-use/). There are no functional
changes to caching provided by these actions: all workflows will
continue to function as before.

The non-caching aspects of action implementation remain open source. By
running these actions with caching disabled they can be used without
ever loading `gradle-actions-caching` or accepting the license terms.

Supporting the caching infrastructure in this project requires a
substantial engineering investment by Gradle Technologies, which we can
sustain thanks to Develocity, our commercial offering. Caching
technologies are a core part of the Develocity offering, and the caching
in `setup-gradle` fits squarely in that space.

This licensing change lets us continue to build advanced capabilities
that go beyond what we would offer as open source. Proper
production-ready Configuration Cache support will be the first
capability. Improving build performance for self-hosted runners will
follow.

We may introduce functionality restrictions in future updates. However,
caching functionality will remain free for public repositories.
We have a long-standing commitment to open source, as maintainers of
Gradle Build Tool, and by [sponsoring the open source
community](https://gradle.com/oss-sponsored-by-develocity/) with free
Develocity licenses. Public repositories are primarily used by open
source projects, and we remain committed to supporting them.

- Implementation of caching logic to save and restore Gradle User Home
content has been removed, replaced by the `gradle-actions-caching`
component.
- The `@actions/caching` library is still used to cache Gradle
distributions that are downloaded and provisioned by `setup-gradle`.
This PR updates to the latest version of `@actions/caching`, and removes
the patch that is no longer required.
- License notices are now displayed in documentation, logs and the
generated Job Summary.

licenses/gradle-actions-caching-license.txt

@@ -0,0 +1,27 @@
+Software License Agreement Copyright (c) 2026 Gradle, Inc. All rights
+reserved.
+
+1. PROPRIETARY AND CONFIDENTIAL. This software and its source code are the
+proprietary and confidential property of Gradle, Inc.
+
+2. LICENSE GRANT AND TERMS OF USE. Subject to your compliance with the Terms
+of Use referenced below, Gradle, Inc. grants you a non-exclusive,
+non-transferable license to use this library solely for internal CI/CD
+purposes. Your use, installation, and distribution of this software are
+strictly governed by the Gradle, Inc. Terms of Use, which can be found at the
+following URL: https://gradle.com/legal/terms-of-use/. By downloading,
+installing, or using this software, you agree to be bound by the terms and
+conditions set forth in the link above.
+
+3. RESTRICTIONS. Unless expressly permitted in the Terms of Use referenced
+above, you may not: (a) Modify, decompile, or reverse engineer this software.
+(b) Redistribute the source code or binaries without prior written consent.
+(c) Use this software for any purpose not authorized by the Terms of Use.
+
+4. NO WARRANTY. AS SET FORTH IN THE GRADLE, INC. TERMS OF USE, THIS SOFTWARE IS
+PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.