### Description

This PR restores Java support on macOS arm64 and fixes Jar testing
failures on the new AcesShared pool.

#### Background

Commit `5ed340f7a51f3cbdb62577a874daf2b3f23d6a93`
(#26252) moved macOS builds
to a faster pool (AcesShared) which reduced build time by 85%, but this
pool doesn't have JDK installed and ADO's `JavaToolInstaller` doesn't
support macOS. As a result, Java binaries for macOS arm64 were
temporarily removed.

#### Changes

1. Enable Java Builds & Tests on macOS ARM64:
* Install JDK 17: Added a script to install JDK 17 via Homebrew if
missing on the agent.
* Install Maven: Added a fallback to install Maven using curl (since
wget is missing on macOS) and configured it to use the * dynamically
resolved JAVA_HOME.
* Pipeline Updates: Updated jar_package_testing.yml and
final-jar-testing-linux.yml to run correctly on AcesShared.
2. Fix C API Tests on macOS ARM64:
* Pool Migration: Updated c-api-noopenmp-test-pipelines.yml to use
AcesShared with the correct ImageOverride.
* Template Enhancements: Updated nuget/templates/test_macos.yml to
support dynamic AgentPool and PoolDemands.
* Fix Missing Artifact: Modified mac-cpu-packaging-steps.yml to
explicitly copy libcustom_op_library.dylib into the testdata folder of
the artifact, resolving DllNotFoundException in EndToEndTests.

### Motivation and Context

To ensure robust CI coverage for macOS ARM64 (Apple Silicon) for both
Java and C APIs effectively using the efficient AcesShared pool.

### Testing

- Final_Jar_Testing_MacOS passed: 

https://dev.azure.com/aiinfra/Lotus/_build/results?buildId=1081961&view=logs&j=f1f8e11e-a9fa-53e5-cd29-3ba2c1988550&t=f4fafe98-de38-519c-0045-d220f6898d47