fix: Support PageableDefault#value()

[daniel-shuy]

@PageableDefault#value is an alias for @PageableDefault#size, but currently, springdoc-openapi is only reading the default size from size, not value.

This change attempts to get the default size from size first. If it is the default value, then it will get the default size from value. I'm not sure if this is the correct precedence, anyone knows if Java annotation parsers normally give higher precedence to value or the aliased parameter?

[bnasslahsen]

Thank you @daniel-shuy for your contribution to the project.

[daniel-shuy]

Thanks @bnasslahsen!

I tested configuring both size and value for PageableDefault on the same parameter, and it looks like Spring gives size the higher priority, as expected.