add option to send host header in HTTP proxy CONNECT command #3221

Job	Run time
build (asio-debugging=on picker-debugging=on)	7m 19s
pre-commit	14s
build (extensions=off logging=off streaming=off super-seeding=off share-mode=off predictive-piece...	5m 24s
build (crypto=gcrypt)	5m 45s
build (mmap-disk-io=off)	6m 50s
check headers	4m 0s
clang-tidy	10m 17s
build dist (ubuntu-20.04)	3m 48s
Fuzzers	8m 37s
build dist (ubuntu-22.04)	3m 16s
Simulations	9m 19s
Tests (address-sanitizer=norecover undefined-sanitizer=norecover crypto=openssl)	6m 27s
Tests (toolset=clang logging=off address-sanitizer=norecover undefined-sanitizer=norecover)	11m 36s
Tests (thread-sanitizer=norecover crypto=openssl release debug-symbols=on cxxflags=-Wno-tsan)	7m 27s
Tests (crypto=gnutls)	5m 18s
Tests (deprecated-functions=off)	4m 57s
	1h 40m 34s

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