Bincrafters-conventions

* Remote update: Don't add [build=outdated] tag anymore
* Update OpenSSL 1.0.2 to patch level 1.0.2u
* Add latest CCI reference updates

* Remove update from Exception to ConanInvalidConfiguration exception as it is too error-prone. Sometimes plain Exceptions are better
* Add updates for recipe references in test_package/conanfile.py
* Add updates for recipe references in build.py
* Add latest CCI reference updates

* Travis: macOS image update from 11.2 -> 11.3
* Add support for updating GitHub Actions workflow files
* Add warning that OpenSSL 1.0.2 is End-Of-Life
* Add latest CCI reference updates

* Fix: When a legacy CI build job is found (32-bit or MinGW) and the bincrafters-conventions:preserve-build-job tag is used on the same build job the job update script isn't applying any changes, but still reporting a update. This can lead to an empty git commit pushed to the remote
* add latest CCI reference updates

* internal: update pip requirements
* fix: typo exit -> exists
* fix: OpenSSL update script shouldn't return true for EOL OpenSSL versions; this can cause the creation of empty commits
* add latest CCI reference updates

* update XCode images 11 -> 11.2
* add Clang 9 builds
* fetch up to 600 repositories from the GitHub api for the remote feature
* update Linux host image Xenial -> Bionic
* remove Clang 7 workaround; use `conanio/clang70` container for new jobs
* remove check for existing readme in the checks features
* delete Bincrafters and Conan Community author attributes
* remote feature: put CI skip tags in the long commit description
* remove standalone CLI feature to update only the readme
* update check for `tools.get()` to look if `conandata.yml` is used
* increase minimum Conan version to 1.18.0 as it is the first version which supports `user/channel` as optional
* fix jobs_update not returning explicit value, causing the remote feature to not push modified files
* add latest CCI reference updates