Deleting items (organizations, products, repositories, secrets etc.) from
the server can be considered dangerous, as deletion is irreversible and
might have unwanted side effects.

Add an optional boolean prop `textConfirmation` to the delete modal.
When it is set to `true`, the user is required to write the name of the
item which is about to be deleted to an input box, before the Delete 
button is enabled.

Signed-off-by: Jyrki Keisala <[email protected]>

PR #1278 extends user creation by adding optional first name, last name
and email to the user information.

Add these fields to the user creation form and mark them as optional.

Signed-off-by: Jyrki Keisala <[email protected]>

Add support for creating, listing and deleting users. Updating user data
wasn't considered to be necessary at this point, so there's currently no
back-end support for it, thus it is also omitted from the front-end.

List users (username, first name, last name, email) in a data table which
is paginated on client-side. Users can be added and deleted from this
view, and because deleting a user might be considered a dangerous
operation, deleting needs manual text input in the delete dialog.

Signed-off-by: Jyrki Keisala <[email protected]>