gh-31: UI, text and validation improvements of the top header, sharing and secrets

[dinukadesilva]

• Fix the last name input label in the profile page.
• Adding a spinner and improve the authentication validation in top header.
• Adding hide/show switches to the password fields in the secrets page.
• Improve the wording of evaluate sharing action label.
• Change the "Owner" columns of entity sharing to "Groups / Users" in the sharing page.