We need to remove exec_program() from our Cmake files

We need to hurry to remove exec_program(....) from our cmake files because
It will be removed with the upcoming CMake's 3.28.0 version which is really
near to release. ( Just 2 hours ago its rc3 was released ).
And from a quick search for our repo ( with ripgrep) I have seen that we
got at least 18 repo using that execure_program(...)

CMake Release Notes :
https://cmake.org/cmake/help/v3.28/release/3.28.html#deprecated-and-removed-features

```
The exec_program()
<https://cmake.org/cmake/help/v3.28/command/exec_program.html#command:exec_program>
command, which has been deprecated since CMake 3.0, has been removed by
policy CMP0153
<https://cmake.org/cmake/help/v3.28/policy/CMP0153.html#policy:CMP0153>.
Use the execute_process()
<https://cmake.org/cmake/help/v3.28/command/execute_process.html#command:execute_process>
command instead.
```


[Sorry for cross post to kde-devel and kde-core-devel ]

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