[core] Add headers to file_get_contents (#1623)
[core] Add headers to file_get_contents (#1623)

Add response headers to file_get_contents() method. Headers are used by some bridges.
ORelio/rss-bridge,Riduidel/rss-bridge,sebsauvage/rss-bridge,RSS-Bridge/rss-bridge,Riduidel/rss-bridge,ORelio/rss-bridge,RSS-Bridge/rss-bridge,kranack/rss-bridge,kranack/rss-bridge,kranack/rss-bridge,ORelio/rss-bridge,Riduidel/rss-bridge,RSS-Bridge/rss-bridge,kranack/rss-bridge