This renames the `id` field of the overworld animation manager to
`userInt`.
This field was initially documented as containing some sort of
caller-defined identifier based on how it was being used in the HM
cut-in file, but it's become more clear that the entire meaning of this
field is caller-defined (see its use by the surf mount renderers as a
boolean).
This also updates the surf mount renderer to correctly identify a flag
that's used to control whether the surf mount position is synchronized
with the player position on tick.
The same changes were ported to the distortion world surf mount renderer
where applicable.
Signed-off-by: Kuruyia <github@kuruyia.net>
