Draft: manager: datamodel: secure use of strings in lua configuration

Since we render the lua configuration with jinja2 template, all string inputs in configuration should be validated or escaped. No generic str type in configuration schema(except lua section).

• new regex for IDPattern
• There are two custom types for string inputs that cannot be strictly validated.
  • EscapedStr - escapes single/double quotes and newlines
  • RawStr - raw representation, escapes all unicode chars and quotes

A simple example of a problem with quotes and newlines:

hostname: "')\nany_lua_code"

Jinja2 template:

hostname('{cfg.hostname}')

Render:

hostname('')
any_lua_code

As a result, kresd startup fails or worse, any_lua_code may be executed.

Are there any other characters or something else I missed that can cause problems? cc @vcunat @ostava

related #715