hard-coded labels make hard to setup local sandboxed environment as the appview won't run until we fill all 5 definitions under TangledDid. so make them configurable with `TANGLED_LABEL_DEFAULTS` which is a list of aturis delimitted by , character we can have any number/kind of default labels but gfi is required for `/good-first-issue` page Signed-off-by: Seongmin Lee <git@boltless.me>