[MRG] Use body to choose response type after decompression content

DOC Mention brotli support in HttpCompressionMiddleware section

Fix referrer policy from response headers and support explicit empty string

Update release notes for 1.0.7, 1.1.4 and 1.2.3

[MRG+1] data URI download handler.

Remove redundant slot.add_request() call in ExecutionEngine

[MRG] Referrer policies in RefererMiddleware

[MRG+1] Set canonicalize=False for LinkExtractor