Add "Export Clang Compilation Database" feature

[egraether]

No description provided.

[studgeek]

For context, this would be similar to the "Create a Clang Compilation Database" in VS Code - https://www.sourcetrail.com/documentation/#CreateaC/C++SourceGroupfromVisualStudioSolution.

One reason it would be beneficial is that CLion has additional information than the underlying build system like what directories the developer has excluded (usually for indexing performance reasons). So exporting from CLion would allow Sourcetrail to stay more in sync and reduce overall indexing time.