style(generated-code): use Self in as_str_name

[thecaralice]

Makes as_str_name generate match self using Self:: where possible, consistent with from_str_name

[caspermeijn]

Thank you for this styling change.

I would like to prevent regression via CI, but I can't think of a way to do it reliably. I would rather not enable clippy::use_self as it is in nursery.

Please change the commit message and title to better reflect the changes. For example:

style(generated-code): Use `Self` in `as_str_name`

[caspermeijn]

Thank you for your contribution