Function fix_param_usages 

fn fix_param_usages(
    editor: &SyntaxEditor,
    source_syntax: &SyntaxNode,
    syntax: &SyntaxNode,
    ctx: &AssistContext<'_, '_>,
    to_this_param: Option<Local>,
    params: &[Param<'_>],
)

change all usages to account for added &/&mut for some params