* Add support for building with MinGW

Tested with MSYS2 MinGW 8.3.0, gcc-mcf.lhmouse MinGW 9.2.1,
and StephanTLavavej/mingw-distro!

* Add MinGW toolchain

From your MinGW configured shell you could just use vcpkg to
configure packages.

An x64-mingw triplet would look like:
```
set(VCPKG_TARGET_ARCHITECTURE x64)
set(VCPKG_CRT_LINKAGE dynamic)
set(VCPKG_LIBRARY_LINKAGE static)
set(VCPKG_ENV_PASSTHROUGH PATH)

set(VCPKG_CMAKE_SYSTEM_NAME MinGW)
```

* Add MinGW community tripplets

x64 tested with https://github.com/StephanTLavavej/mingw-distro
x86, arm64, arm tested with https://github.com/mstorsjo/llvm-mingw

* Move untested triplets to Community Triplets

* Document community triplets

* Load community triplets by default and alert when using one

* [triplets] Merge documentation of community triplets

* Bump version

To install a specific version of a package via homebrew, an `@` symbol must be placed in-between the package name and its version.
Added missing symbol to `toolsrc/CMakeLists.txt`

See homebrew console output for reference:
```
Kristofs-Mac-Pro:vcpkg kristofdaja$ brew search gcc
==> Formulae
gcc                     gcc@5                   gcc@7                   x86_64-elf-gcc
gcc@4.9                 gcc@6                   gcc@8
```

* fixes to get vcpkg up and running when behind corporate proxy

* clean up of code to check if HTTP_PROXY environment variable is set

*  fixed compiler errors for non win32 systems

* [vcpkg] Simplify HTTPS_PROXY code for WinHTTP

Co-authored-by: Robert Schumacher <roschuma@microsoft.com>

* - Introduce new policy to skip post verification of dll exports (see issue #9641).

* - Fixed line endings.

[vcpkg] update telemetry