Add a new test "search"

[DCAuto]

This test will be the inverse of "in". Primary use will be for the selectattr filter to search for substrings in a list of dictionaries.

Example:
Given the following list of dictionaries:

test_list = [
    {"name": "John"},
    {"name": "Jose"},
    {"name": "Beth"},
    {"name": "Jake"},
]

Within the template, extract list items that have the sub-string "Jo" in the "name" key:

{{ test_list | selectattr("name", "search", "Jo") | list }}

[davidism]

Duplicate of #1766