feat(folders): propagate default language

[kaftanati]

Adds a folder language update dialog with optional propagation to nested folders and snippet contents.

[kaftanati]

The implemented functionality addresses the need to set a default language for nested folders and files when a language is specified for a non-empty folder. This feature is optional and is activated only by selecting the checkboxes in the mini-dialog that appears after changing the default language for a folder.

I encountered this requirement when I could not find a way to bulk-set the language for all files within the snippets folder.

[kaftanati]

[antonreshetov]

Thanks for the PR and for taking the time to work on this! We usually discuss new features before implementation so we can agree on the use case and approach, as outlined in our contributing guide.

Could you open a discussion describing the workflow you’re trying to improve? That would help us decide how this should fit into massCode.