Fix UnsupportedOperationException in executeAdminDomainCommand for postBootCommands with arguments

[jcputney]

Fixes #36.

Problem

executeAdminDomainCommand mutates its caller-supplied args list via args.add(config.getDomain()). Callers from start() (post-boot-commands loop) and stop()/stopContainer() pass immutable lists from Arrays.asList(...) and List.of(), so this throws UnsupportedOperationException at runtime — surfacing most visibly at @AfterSuite teardown.

Fix

Defensive copy of args inside executeAdminDomainCommand. The method no longer mutates caller state, and immutable inputs work as expected.

Tests

Adds GlassFishServerControlPostBootCommandsTest with three cases covering both immutable list flavors (Arrays.asList, List.of). Verified to fail with UnsupportedOperationException without the fix
and pass with it.

Scope

One-line behavior change + targeted unit test. No reformatting, no unrelated edits.