feat(ngPluralize): add support for bind-once in `count`

The 1st commit contains the change and test for adding support for `bindOnce` in `count`.
The 2nd commit contains some nimor refactoring (mainly to avoid repetitive actions).

Closes #10004
(Makes #5452 obsolete)
The previous implementation was without interceptors (but used an extra local variable).
So, it is doable (remains to see if it is desirable).

@caitp: Why remove interceptors ? They seem pretty cool :) What's the catch ?