[WebNN] Support SkipSimplifiedLayerNormalization op (#23151)
The algorithm of `SkipSimplifiedLayerNormalization` is quite similar to
the `SimplifiedLayerNormalization`, only different is
`SkipSimplifiedLayerNormalization` provides an additional output used
for calculating the sum of the input, skip and bias (if it exits).
BTW, fix a bug in `SimplifiedLayerNormalization`, adding bias if it
exits.