Add flexsearch module and sample program with edge case handling

[KailashSatkuri-warangal]

• Added Lib/flexsearch.py: a Python module to parse numbers from strings, sort arrays
  (modes: a/d/min/max), and perform binary search with automatic ascending/descending detection.
• Added Programs/samplebinarysearch.py: interactive demo program for testing the module.
• Handles edge cases including empty input, non-numeric input, missing target, duplicates,
  single-element arrays, and mixed separators.
• Fully tested with interactive user input; ready to run with local CPython build.

This adds a reusable module for numeric parsing, sorting, and searching to the forked CPython repository.

[python-cla-bot]

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[StanFromIreland]

You accidentally opened this against upstream and not the fork you mentioned IIUC.