plugins.afreeca: use 'gs_cdn_pc_web' and 'common'
plugins.afreeca: use 'gs_cdn_pc_web' and 'common'

gs_cdn --> gs_cdn_pc_web
flash  --> common

the api returns `gs_cdn` but it doesn't work with every region.
use `gs_cdn_pc_web` instead.

gravyboat/streamlink,gravyboat/streamlink,bastimeyer/streamlink,bastimeyer/streamlink,melmorabity/streamlink,melmorabity/streamlink,chhe/streamlink,streamlink/streamlink,streamlink/streamlink,chhe/streamlink