derive-msg-formats 5/5: Remove placeholder implementations

# This commit has been generated via the following Python script:
# (followed by `cargo +nightly fmt` and `cargo dev generate-all`)
# For the reasoning see the previous commit(s).

import re
import sys

for path in (
    'src/violations.rs',
    'src/rules/flake8_tidy_imports/banned_api.rs',
    'src/rules/flake8_tidy_imports/relative_imports.rs',
):
    with open(path) as f:
        text = ''

        while line := next(f, None):

            if line.strip() != 'fn message(&self) -> String {':
                text += line
                continue

            text += '    #[derive_message_formats]\n' + line

            body = next(f)
            while (line := next(f)) != '    }\n':
                body += line

            # body = re.sub(r'(?<!code\| |\.push\()format!', 'format!', body)
            body = re.sub(
                r'("[^"]+")\s*\.to_string\(\)', r'format!(\1)', body, re.DOTALL
            )
            body = re.sub(
                r'(r#".+?"#)\s*\.to_string\(\)', r'format!(\1)', body, re.DOTALL
            )

            text += body + '    }\n'

            while (line := next(f)).strip() != 'fn placeholder() -> Self {':
                text += line
            while (line := next(f)) != '    }\n':
                pass

    with open(path, 'w') as f:
        f.write(text)