ToDo user search does not work as expected when first name and last name contain spaces

[DHaussermann]

The ToDo user search for the send functionality is different from the user picker elsewhere in Mattermost and the search does not work as expected if the target user has a space in their first or last name.
The generic user search will still return relevant users when the value includes a space but, the ToDo user search does not.

Steps:

• Create a target user with a first name such as Jean Luc
• Login as another user
• Create a ToDo and use Jean Luc as the user you are sending the ToDo to
  Observed: Once you add a Character after the space the first name no longer matches the target user