Import MDC #5367 by asyncLiz: fix(textfield): add separate classes for leading/trailing icons
Import MDC #5367 by asyncLiz: fix(textfield): add separate classes for leading/trailing icons

PR:
  go/mdc-web-pull/5367

Description:
  BREAKING_CHANGE: icons must use `.mdc-text-field__icon--leading` or `.mdc-text-field__icon--trailing` classes. `mdc-text-field-icon-color()` mixin has been split into `mdc-text-field-leading-icon-color()` and `mdc-text-field-trailing-icon-color()`.
Tested:
  https://test.corp.google.com/ui#id=OCL:287554248:BASE:288701267:1578500687772:eaf3ab49
COPYBARA_INTEGRATE_REVIEW=https://github.com/material-components/material-components-web/pull/5367 from material-components:fix/textfield/leading-trailing-icon-classes 3bf0ec97cba823052241450b65ae1edb3af18963
PiperOrigin-RevId: 288741151

material-components/material-web,material-components/material-web