Problem: filetype: Asymptote files are not recognized
Solution: detect '*.asy' files as asy filetype, include
ftplugin and syntax plugin (AvidSeeker).
Reference: https://asymptote.sourceforge.io/closes: #15252
Signed-off-by: AvidSeeker <avidseeker7@protonmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
