Index name colliding

I have tables like this:

#[spacetimedb::table(accessor = product_category, public)]
pub struct ProductCategory {
    #[primary_key]
    #[auto_inc]
    pub id: u64,
    #[index(btree)]
    pub store_id: u64,
    pub name: String,
}

#[spacetimedb::table(accessor = product, public)]
pub struct Product {
    #[primary_key]
    #[auto_inc]
    pub id: u64,
    #[index(btree)]
    pub store_id: u64,
    #[index(btree)]
    pub category_id: u64,
    pub name: String,
    pub description: Option<String>,
    pub price: u128,
}

it compile just fine when using spacetime build
but when I spacetime publish it return error:

name product_category_id_idx_btree is used for multiple entities

From what I see its because of the index is generated by {accessor}_{field}_idx_btree, so it output the same product_category_id_idx_btree for both of the table. It's nice if we can specify the name of index with something like

#[index(btree, name="prod_category_id_idx_btree2")]

or maybe even better automagically handle that colliding name in macros

oh, after reading the spactimedb code I see the index name will auto generated with this format:
{table_name}_{cols}_idx_{algo}
maybe the simple fix is to change the separator to be double __:
{table_name}__{cols}_idx_{algo}
or use another character for separator, I don't know, what do you think?

Start from the index-name generation used by the #[index(btree)] attributes and compare the spacetime build and spacetime publish paths for the supplied ProductCategory and Product tables. Done means these tables publish successfully without the product_category_id_idx_btree duplicate-name error; linked pull request 4725 indicates work is already underway.