Add NIO channel support to AbstractStreamBuilder (#784)

* feat: add NIO channel support to `AbstractStreamBuilder`

Some builders derived from `AbstractStreamBuilder` (for example, `SevenZFile.Builder` in Commons Compress) need to produce a `SeekableByteChannel` as their data source. Until now this required ad-hoc `instanceof` switches across different origin types.

This change integrates channel support directly into the origin/builder abstraction, leading to a cleaner and more object-oriented design.

### Key changes

* Add `getReadableByteChannel()` and `getWritableByteChannel()` to `AbstractOrigin` and propagate to `AbstractStreamBuilder`.
* Introduce `ChannelOrigin`, an `AbstractOrigin` implementation backed by an existing `ReadableByteChannel`/`WritableByteChannel`.
* Add `ByteArrayChannel`, a simple in-memory `SeekableByteChannel` implementation.
* Extend unit tests to cover the new methods and types.

* fix: cleanup on Windows

* fix: checkstyle violation

* fix: merge `ByteArrayChannel` and `ByteArraySeekableByteChannel`

* fix: failing test

* fix: remove irrelevant changes

* fix: changelog

* fix: make `data` private

* fix: refine `ByteArraySeekableByteChannel` Javadoc

Clarifies the Javadoc to better reflect the intended usage patterns:

* `wrap(byte[])` is modeled after `ByteArrayInputStream` and is primarily for read-oriented use.
* The public constructors `ByteArraySeekableByteChannel()` and `ByteArraySeekableByteChannel(int)` follow the pattern of `ByteArrayOutputStream` and are mainly suited for write-oriented use.

* fix: add missing `@Override` annotation

* fix: typo in default size value

* feat: add generic `getChannel(Class<C>)` accessor

Adds a type-safe `getChannel(Class<C>)` method that lets callers request any supported `Channel` subtype (e.g. `ReadableByteChannel`, `WritableByteChannel`, `SeekableByteChannel`) through a single entry point.

* fix: rename `doGetChannel` to `getChannel`

* fix: Javadoc

* fix: default capacity of `ByteArraySeekableByteChannel`

* fix: rename `getTestData` to `cloneTestData`

* docs: minimum channel type by origin

* fix: make `getChannel` final

* fix: don't clone `testData`

Cloning the test data is unnecessary as all but one test are not supposed to modify them.

* fix: test order

Author: ppkarwasz

src/changes/changes.xml

@@ -63,9 +63,10 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add org.apache.commons.io.output.ProxyOutputStream.writeRepeat(int, long).</action>
       <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add length unit support in FileSystem limits.</action>
       <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add IOUtils.toByteArray(InputStream, int, int) for safer chunked reading with size validation.</action>
-      <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add org.apache.commons.io.file.PathUtils.getPath(String, String).</action>
+      <action dev="ggregory" type="add"                due-to="Gary Gregory">Add org.apache.commons.io.file.PathUtils.getPath(String, String).</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add org.apache.commons.io.channels.ByteArraySeekableByteChannel.</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add IOIterable.asIterable().</action>
+      <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add NIO channel support to `AbstractStreamBuilder`.</action>
       <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add CloseShieldChannel to close-shielded NIO Channels #786.</action>
       <!-- UPDATE -->
       <action type="update" dev="ggregory"             due-to="Gary Gregory, Dependabot">Bump org.apache.commons:commons-parent from 85 to 88 #774, #783.</action>