fix(ux): remove tax rate from invoice breakdown

[18alantom]

Removed display of tax rate from the tax breakdown section.

Why

• One would be more concerned with how much is paid for each tax.
• Item-wise breakdown on the invoice level is cluttersome.
• This information can be displayed at the item level, will add this later by allowing row expansion.

(created a PR to add the above message)

[18alantom]

Renders #141 redundant.