Add a cacheable no-op scalar normalizer

[teohhanhui]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets	#2593 (partially)
License	MIT
Doc PR	N/A

/cc @bastnic

[teohhanhui]

Screenshots of Blackfire profiles, for comparison:

without NoOpScalarNormalizer

with NoOpScalarNormalizer

This is with an empty cache in prod environment, with 8 items of the dummy Greeting entity included in api-platform/api-platform, with an added getNumbers generator method which yields 0-999 (lol)

[bastnic]

nice!

For the fun, did you try just moving the is_scalar ... return check before the getNormalizer in Serialier::normalize?

[teohhanhui]

For the fun, did you try just moving the is_scalar ... return check before the getNormalizer in Serialier::normalize?

No, we cannot do that. :)

[bastnic]

of course... at least with the current serializer implementation.

[soyuka]

This is good! Thanks @teohhanhui @bastnic