[QNN EP] Improve QDQ model accuracy tests (#16916)
### Description
- Improves how unit tests measure the accuracy of QDQ models on QNN EP.
- Adds tests for ops: Add, Mul, Abs<sup>1</sup>, And<sup>1</sup>,
Or<sup>1</sup>, Ceil<sup>1</sup>, Cos<sup>1</sup>
<sup>1</sup>: Not previously supported due to missing node unit
handling.
### Motivation and Context
The new approach for testing QDQ operator accuracy requires running 3
inferences:
1. float model on CPU EP (baseline)
2. qdq model on CPU EP
3. qdq model on QNN EP
The units tests check that running the QDQ model on QNN EP (3) is at
least as accurate (+- small tolerance) as running the QDQ model on CPU
EP (2). We measure accuracy by comparing to the baseline (1).
This is essentially what we care about: is qnn ep as accurate as cpu ep.
If not, it is worth investigating as a potential bug.
