Button - additional padding and margin options

[mkernohanbc]

Feedback from developer.gov.bc.ca team on the button component:

You may need to account for left and/or right padding on the tertiary and link buttons so that they align with content appropriately (it kinda drives designers wild when it doesn't, and we found a lot of folks 'hacking' the buttons to align)

Additional note from @ty2k:

the tertiary buttons don't have a visible border, but they do have a hover state that gives them a grey background with the rounded corners like the primary/secondary buttons. The link button doesn't have a background that changes, but it still has that same padding? Do you figure both of those button options need a way for folks to say "no horizontal padding or "no padding on one side" to give folks the option to get alignments just so?

Suggested using css:after to implement hover state without changing the size of the component.

Need to investigate best way to give users option to override padding without completely breaking the component.