Fix link anim export

[Dragorn421]

There were several bugs and missing features:

1. the folderName was still being checked even though isLink=True means it doesn't play a role (the UI doesnt display it)
2. ootGetObjectPath was called for isLink=True with the folderName which again isn't relevant for link anims exports
3. assets/misc/link_animetion/ and assets/objects/gameplay_keep/ were not being created if missing (which is the case post "new" assets system)
4. link_animetion.c and gameplay_keep.c were being created in the case of "new" assets system tm, when the proper thing to do is to just export the .c to assets/ and link the relevant .o files in the spec, which is now done in this PR

[Yanis002]

seems to work properly

so I guess the order doesn't matter? that's good to know 💪
I'm not particularily fan of this filename format but I can live with it, also I just realised the custom filename option isn't working for some reasons

[Dragorn421]

yeah the spec commands can be in any order
I just put the new includes last because it made processing the spec much much easier, and I figured anyone relying on fast64 to autoupdate the spec wouldnt care anyway

the filename format is not changed in this pr, that's what it was before
I agree it leaves room for improvement (but out of scope)

[Dragorn421]

I ended up hiding the "custom filename" option (if exporting link anims), because link anims are made of two sets of two files, so specifying a single custom filename can't work