[QNN EP] Fix Clip op with min or max from QDQ (#26601)
## Motivation
QDQ node group selection logic currently navigate `Clip` op to
`UnaryNodeGroupSelector`. This isn't properly handling the use case
where `Clip` op has `min/max` provided from Q/DQ ops (still constant
initializers).
<img width="255" height="378" alt="image-2025-11-18-11-49-19-156"
src="https://github.com/user-attachments/assets/ec6250ee-68f3-40fa-8f60-93b1a400d5a0"
/>
## Changes:
- Implement custom NodeGroupSelector so that `Clip` op is properly
tagged for backend to consume.
- Fix QNN EP `Clip` min/max parsing and perform de-quantize when needed.
- Unit tests for both changes.
