feat: `AmountInput` UI, disabled and error states

[karelianpie]

Description

Amount input component:

• Match colors and spacings to designs
• Disabled state
• Error state (red border)

Motivation and Context

Match designs

How Has This Been Tested?

Ran locally and observed the changes, refer to screenshots below

Screenshots (if appropriate):

[karelianpie]

@xgambitox did the style changes we've discussed yesterday (https://github.com/yearn/yearn-finance-v3/pull/730/commits/a288711cb3767b951ea9b518eb66a9cf5588ecd5) also noticed that in Figma when disabled the max button is not displayed (https://github.com/yearn/yearn-finance-v3/pull/730/commits/edd26d6d9b53cc93399683112ca17d21ce477910) see below.

Finally also added cursor: not-allowed; to make it clear it's disabled (https://github.com/yearn/yearn-finance-v3/pull/730/commits/8deff5478e955971e5d157387d7d0d1892017f9c).

Light theme

Enabled amount input

Disabled amount input

Dark theme

Enabled amount input

Disabled amount input