[Solver] Check all output branches are quantized before merging quantizers

[daniil-lyakhov]

Changes

Quantizer merge logic updated to check that all output branches are quantized before quantizers merging and propagating up.

Reason for changes

To prevent merging of quantizers in case of ScaledDotProductAttention op, which should have quantizers on [0, 1] input ports and shouldn't have a quantizer on the 3 input port.

Related tickets

148211
#2766

Tests

• Common solver test for ScaleDotProductAttention branch merging and quantization initialization
• Graph tests for torch/ov backends

[daniil-lyakhov]

Scale dot product attention quantization:
Before: quantizers are being merged and propagated up besides the fact that one of the branches is not quantizable

After: quantizers are not merged, quantization scheme is correct

CC: @KodiaqQ

[daniil-lyakhov]

bloomz-560m quantization with not fused ScaledDotProductAttention op checked locally