build: Revamp RECOVERY_NEEDS_SUPPORT_IMG flag logic

- Conditionally include vendor_boot.img when RECOVERY_NEEDS_VENDOR_BOOT_IMG is set
- Most OnePlus devices depend on dtbo and vbmeta for recovery to boot up hence having only these files make sense.
- Zip them up with recovery-*.zip so that it looks clean and neat on download page.

Signed-off-by: Jackeagle <jackeagle102@gmail.com>