Implements the corresponding encoders, selects the appropriate one when
encoding URL search params. If an encoder for the given encoding could
not be found, fallback to utf-8.
If no header includes the prototype of a function, then it cannot be
used from outside the translation unit it was defined in. In that case,
it should be marked as `static`, in order to avoid possible ODR
problems, unnecessary exported symbols, and allow the compiler to better
optimize those.
If this warning triggers in a function defined in a header, `inline`
needs to be added, otherwise if the header is included in more than one
TU, it will fail to link with a duplicate definition error.
The reason this diff got so big is that Lagom-only code wasn't built
with this flag even in Serenity times.
The Encoding specification maps ISO-8859-1 to windows-1252 and expects
the windows-1252 translation table to be used, which differs from
ISO-8859-1 for 0x80-0x9F.
Other contexts expect to get the actual ISO-8859-1 encoding, with 1-to-1
mapping to U+0000-U+00FF, when requesting it.
`decoder_for_exact_name` is introduced, which skips the mapping from
aliases to the encoding name done by `get_standardized_encoding`.
