Allow toggling code lens positions

[Kixiron]

Currently code lenses are positioned between doc comments/attributes and the item they're decorating, like this

But I personally would rather it be above the doc comments and attributes, so an option to toggle their position would be awesome

[Veykril]

Relevant code is here (minus the config part)

rust-analyzer/crates/ide/src/annotations.rs

Lines 123 to 134 in b7e8b9a

	fn name_range<T: HasName>(
	db: &RootDatabase,
	node: InFile<T>,
	source_file_id: FileId,
	) -> Option<TextRange> {
	if let Some(InFile { file_id, value }) = node.original_ast_node(db) {
	if file_id == source_file_id.into() {
	return value.name().map(|it| it.syntax().text_range());
	}
	}
	None
	}

For this new case we should just take the range of the whole node instead of the name, that should make editors place it above the comments and attributes. This should as stated be done with a config flag toggling the behavior, with the current behavior staying the default.

[mdx97]

I'm working on this one but am running into an issue regarding how to configure this feature.

I figured it would be best to add a new enum configuration value. I've called this lens_annotation_location, which now will have values of above_name and above_whole_item (naming can be hashed out in the PR, just giving this information for context).

I'm not exactly sure where to put the Rust enum definition at, however. I need access to this type in both the ide and rust-analyzer crates. But there are problems with either option:

• I can't really put the type in rust-analyzer because it depends upon the ide crate, which would result in a circular reference between the two crates.
• Having a config type exist in the ide crate doesn't seem to be a common pattern of the project. I'd have to add serde as a dependency of ide, which feels weird for this one-off scenario.

Does anyone have opinions?

[Veykril]

usually we define the enum twice, once in IDE as the actual used thing, and the second time just for deserializing purposes in the config module in rust-analyzer, and then we map between the two. Thre should be some enum in config.rs doing this already.