Fix vcpkg config and usage

[ELeeScape]

Newer versions of vcpkg require a builtin-baseline setting that specifies the minimum versions of all packages, as described here: https://learn.microsoft.com/en-us/vcpkg/users/versioning#baselines and here: https://learn.microsoft.com/en-us/vcpkg/reference/vcpkg-json#builtin-baseline. Without this setting, bootstrap-vcpkg.bat errors out with this message:

[...]
-- Running vcpkg install
error: this vcpkg instance requires a manifest with a specified baseline in order to interact with ports. Please add 'builtin-baseline' to the manifest or add a 'vcpkg-configuration.json' that redefines the default registry.
-- Running vcpkg install - failed
[...]

The environment variable that contains the location of the vcpkg tool is VCPKG_ROOT, not VCPKC_DIR, and the path may contain spaces so it needs to be quoted.