Fix blocking reads from System.in in command line execution

[Copilot]

Command line execution blocks indefinitely when using System.in due to StreamFeeder performing blocking read() operations. This applies the same fix as maven-shared-utils MSHARED-1072.

Changes

• New StreamPollFeeder class: Polls InputStream.available() before reading, with 100ms wait intervals when no data is available
• CommandLineUtils updated: Uses StreamPollFeeder instead of StreamFeeder for feeding system input to process output streams
• StreamFeeder deprecated: Kept for backward compatibility with clear migration path

Technical approach

The blocking behavior occurs because StreamFeeder.read() waits indefinitely for input:

// Old: blocks forever on System.in
int data = input.read();

New approach polls for available data:

// New: non-blocking poll with timeout
if (input.available() > 0) {
    int i = input.read(buf);
    output.write(buf, 0, i);
    output.flush();
} else {
    lock.wait(100);  // Poll every 100ms
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>Poll data from input stream</issue_title>
<issue_description>In order to fix blocking command line execution with leveraging system input stream the same fix applied to https://github.com/apache/maven-shared-utils/pull/140/files (https://issues.apache.org/jira/browse/MSHARED-1072) should be done for plexus-utils as well.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Poll data from input stream #260

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