feat: make generated code more idiomatic to zig users

[nilslice]

Convert any end-user facing identifier to a more Zig-friendly option, using the latest helpers in xtp-bindgen. e.g.:

For this schema portion:

snake_case_func_name:
    description: This is a function that uses snake case in the name
    input:
      type: string
      contentType: text/plain; charset=utf-8
      description: A string passed into plugin input
    output:
      $ref: "#/components/schemas/some_value"
      contentType: application/json
#...
components:
  schemas:
    some_value:
      properties:
        a_string:
          type: string
          description: a string

We now produce:

/// This is a function that uses snake case in the name
/// It takes []const u8 as input (A string passed into plugin input)
/// And returns SomeValue ()
pub fn snakeCaseFuncName(input: []const u8) !schema.SomeValue {
    // TODO: fill out your implementation here
    _ = input;
    return error.PluginFunctionNotImplemented;
}

[zshipko]

LGTM - i like the zig*Name wrappers, makes it much easier to tell what's going on