Function plan_move 

pub async fn plan_move(
    ctx: &RefactoringContext,
    from_rel_path: &str,
    to_rel_path: &str,
    symbol_name: &str,
    reexport: bool,
) -> Result<MoveOutcome, String>

Build a move plan without touching the filesystem.

from_rel_path is the relative path to the source file containing the symbol. to_rel_path is the relative path to the destination file. symbol_name is the unqualified name of the symbol to move.