Specifying 'all' is not necessary and does not work on Windows. On Windows the target is called BUILD_ALL.

Fixes issue #95

- exports_source had to be adjusted
- CMakeLists and conanfile.py of test_package is still broken

See https://github.com/conan-io/conan-center-index/issues/20561

- copying of binaries didn't work (protoc, grpc_cpp_plugin)
- boost requirement was not right

Squashed commit of the following:

commit 5f1e1889
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Thu Sep 1 13:35:05 2022 +0200

    PIPELINE

commit 911a16c5
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Thu Sep 1 11:48:55 2022 +0200

    PIPELINE

commit a737a9bb
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Thu Aug 18 13:16:37 2022 +0200

    PIPELINE

commit b4c22e71
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Thu Aug 18 12:15:50 2022 +0200

    PIPELINE

commit 0e13e9ae
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Wed Aug 17 13:23:37 2022 +0200

    PIPELINE

commit 4806355a
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Wed Aug 17 13:20:45 2022 +0200

    PIPELINE

commit cbf9be36
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Wed Aug 17 12:51:25 2022 +0200

    PIPELINE

commit 7415b226
Author: Timm Fitschen <t.fitschen@indiscale.com>
Date:   Mon Aug 15 19:20:45 2022 +0200

    PIPELINE

Also some formatting.