Clean up Button component

[pswu11]

(this is not top priority but it's probably a good practice?)

• [x] clean up unused button sizes (we have 5 sizes, but only used 3)
• [x] fixed width such as w-[90px] shouldn't be used, use px plus minimal width instead so it's flexible
• [x] integrate textStyles to sizeStyles (textStyles here is not used at all)
• [x] make sure that where all the Buttons are used are also updated accordingly with no errors