Add escape like helper

[gaborbernat]

This helper method should be part of the lib:

def escape_like(text: str) -> str:
    """Escape text for like.

    :param text: the raw text
    :return: escaped text
    """
    return text.replace("%", "\\%").replace("_", "\\_")

Example of other frameworks having this https://sqlalchemy-utils.readthedocs.io/en/stable/orm_helpers.html#escape-like

Or at least documented somewhere...

[godlygeek]

I'm reluctant to add this as a function to the library because it's fairly trivial, and more importantly because it won't work out of the box (you need to not only call this escape_like function on your input, but also use the 3 argument form of LIKE where you pass an ESCAPE \ as well).

I'm comfortable adding this to the docs, though. I'll add a bullet to the tips page, and I'll link to that from the .execute method of comdb2.dbapi2.Cursor and comdb2.cdb2.Handle.

[godlygeek]

This also needs to escape any \ in the input text. I think it ought to be either:

return text.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")

or

return re.sub(r"(?=[\\_%])", r"\\", text)

or

return re.sub(r"([\\_%])", r"\\\1", text)