Add keyword search in filter option

[nabaco]

The official Todoist documentation talks about the ability to use a filter with a free text search of keywords, as can be seen here: https://todoist.com/help/articles/introduction-to-filters#filtering-based-on-keywords.
I'd like to have the same supported in the CLI. E.g:

todoist list --filter "search: email"

If one needs to search for a specific task, fzf/peco integration works quite fine. But for scripting, or predefined filters to use as an alias it isn't suitable.

[kenliu]

Good suggestion, thanks!