Enable clangd for all projects that belong to context-set

[ReinhardKeil]

Currently only the first project of a context-set is part of the file .vscode\settings.json, for example:
{
"clangd.arguments": [
"--compile-commands-dir=c:\w\MDK-Middleware\.ci\out\FileSystem\CM4\Debug"
]
}

This clangd.arguments list should contain all projects that are selected in the cbuild-set.yml file which reflects the current selected context-set.