Content: "Lastname" to be two words instead of one in error message "Last name is required"

**Describe the task**
As a _ministry_ user, _I want_ the grammar to be consistent with spacing _so that_ I can quickly read it

**Acceptance Criteria**
- [ ] Change message from "Lastname is required" to "Last name is required" (TBD 'name' is most likely to be sentence case)

Release 1.15

TC 4144