[opentelemetry-cpp] build failure (Unknown CMake command "find_dependency")

[klalumiere]

Operating system

Ubuntu 22.04

Compiler

Clang

Steps to reproduce the behavior

`cmake -B build -S test_cpp_project` with a manifest `vcpkg.json`


{
    "name": "testcppproject",
    "version-string": "head",
    "overrides": [],
    "dependencies": [
        {
            "name": "opentelemetry-cpp",
            "version>=": "1.8.3#5",
            "features": [
                "otlp"
            ]
        }
    ]
}


a configuration file `vcpkg-configuration.json`

```json
{
    "default-registry": {
        "kind": "builtin",
        "baseline": "c74f7879a6bafc001f7668163b6db4588787f065"
    },
    "registries": []
}

and, inside CMakeLists.txt

find_package(opentelemetry-cpp CONFIG REQUIRED)

### Failure logs

```shell
CMake Error at /home/klalumiere/src/coveo/cpp/cmakelibrary/build/vcpkg_installed/x64-linux-dynamic/share/opentelemetry-cpp/opentelemetry-cpp-config.cmake:86 (find_dependency):
  Unknown CMake command "find_dependency".
Call Stack (most recent call first):
  /home/klalumiere/src/vcpkg/scripts/buildsystems/vcpkg.cmake:852 (_find_package)
  TestTarget/CMakeLists.txt:13 (find_package)

Additional context

I understand the error. We add find_dependency(absl) in opentelemetry-cpp-config.cmake.in, but we forgot include(CMakeFindDependencyMacro). I tested and adding manually include(CMakeFindDependencyMacro) mitigates the issue. I'll open a pull request in a few minutes that solves the issue.