[GPU] use ParallelReadStreamBuf to boost file reading latency

[riverlijunjie]

Details:

Create a custom std::streambuf subclass that internally uses parallel I/O for large reads, exposing a standard std::istream-compatible interface. Any code that currently accepts a std::istream& gets the speedup transparently — no per-plugin changes required.

Tickets:

• https://jira.devtools.intel.com/browse/CVS-179677

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