RFR: Add `--library-path-resolver` option for custom library path resolving

[devjeonghwan]

#### 1. Status Quo

Currently, `jextract` generates code using two standard loading mechanisms:

1.  **Default:** `SymbolLookup.libraryLookup(System.mapLibraryName("name"), ...)`
2.  **With `--use-system-load-library`:** `System.loadLibrary("name")`

Both methods depend on static paths (e.g., `java.library.path`) and do not support runtime path resolution (hooking) without manual code modification.

#### 2. Problem

Standard loading fails in dynamic deployment scenarios:

  * **Bundled Libraries:** Native libraries inside JARs (extracted to temp directories) require loading from an absolute path.
  * **Dynamic Paths:** Paths determined at runtime based on OS/Arch cannot be handled by static system properties.

Users currently must manually edit the generated source to inject custom loading logic.

#### 3. Fix

Introduced a new CLI option: `--library-path-resolver`.
This option injects a user-defined static method to resolve the library path (or name) at runtime.

**Usage:**


jextract ... --library-path-resolver com.example.Resolver#resolvePath


**Code Generation:**

**Case 1: Default (SymbolLookup)**


// Before
SymbolLookup.libraryLookup(System.mapLibraryName("foo"), ARENA);

// After
SymbolLookup.libraryLookup(com.example.Resolver.resolvePath("foo"), ARENA);


**Case 2: With `--use-system-load-library`**


// Before
System.loadLibrary("foo");

// After
System.load(com.example.Resolver.resolvePath("foo"));


#### 4. Additional Notes

  * **Method Signature:** The resolver method must match `String <method_name>(String <parameter_name>)`.
  * **Return Value:**
      * For `--use-system-load-library`: Must return an **absolute path** (required by `System.load()`).
      * For Default: Returns a path or name accepted by `SymbolLookup`.

#### 5. Testing

Added `TestLibraryPathResolver`.

  * Dynamic compilation and loading of a custom resolver class.
  * Correct code generation when the option is present.
  * Verifying that the custom resolver is actually invoked and that the native library is successfully loaded and linked via the resolved path

All tests pass locally.

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

Commit messages:
 - Remove trailing whitespace in `TestLibraryPathResolver.java`
 - Refactor and rename library path resolver test
 - Add test for custom library path resolver functionality
 - Support custom library path resolvers in system library loading

Changes: https://git.openjdk.org/jextract/pull/295/files
  Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=295&range=00
  Stats: 193 lines in 10 files changed: 176 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/jextract/pull/295.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/295/head:pull/295

PR: https://git.openjdk.org/jextract/pull/295