use ziti-builder image's vcpkg

[qrkourier]

the ziti-builder image provides a stable major release tag that always has latest vcpkg

1. change the cmake composite action, which runs in the ziti-builder container image, to use the provided vcpk instead of re-installing a decoupled version of vcpkg
2. change the cpack builder images to copy vcpk from the latest release of ziti-builder instead of installing a decoupled version
3. configure dependabot to bump the version of the ziti-builder source image in cpack builder images' Dockerfiles