http/2, http/3, decouple stream state from easy handle

[icing]

• add convenience functions to hash.h for using a hash with curl_off_t as keys. Use this in h2+h3 connection filters to associate data->id with the internal stream state.
• changed implementations of all affected connection filters
• removed h2_ctx* and h3_ctx* from struct HTTP and thus the easy handle
• solves the problem of attaching "foreign protocol" easy handles during connection shutdown

[icing]

Separate hash implementation removed again. Convenience functions added.

[bagder]

merge conflicts now after some other merges

[icing]

curl-for-win fails with:

++ gpg --batch --keyserver-options timeout=15 --display-charset utf-8 --keyid-format 0xlong --verify-options show-primary-uid-only --verify pkg.sig pkg.bin
gpg: can't open signed data 'pkg.bin'
gpg: can't hash datafile: No such file or directory

Anyone has an idea what is going on here? @vszakats ?

[vszakats]

Package or signature downloads from GitHub failed:

++ curl --disable --user-agent '' --fail --silent --show-error --globoff
  --remote-time --xattr --connect-timeout 15 --max-time 60 --retry 3
  --max-redirs 10 --location --proto-redir =https --output pkg.bin
  https://github.com/rockdaboot/libpsl/releases/download/0.21.5/libpsl-0.21.5.tar.gz
  --output pkg.sig
  https://github.com/rockdaboot/libpsl/releases/download/0.21.5/libpsl-0.21.5.tar.gz.sig
curl: (22) The requested URL returned error: 500
curl: (22) The requested URL returned error: 500
curl: (22) The requested URL returned error: 500
curl: (22) The requested URL returned error: 500

A retry should fix this.

[vszakats]

Made downloads bail out early with a clear error: curl/curl-for-win@5c09843?w=1