Escape double quotes in ifgen strings.
Escape double quotes in ifgen strings.

When generating a string constant for C in ifgen, also escape double
quotes, which is not done by the python string_escape encoding.

Resolves: LE-7730
Change-Id: I468101833d53bcd928148ecdc1886d94e3f8ad0e

legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af