investigation: accessibility violations reported by axe

[unekinn]

We should go through these stories and determine why we get accessibility violations.

Find the story in Storybook, and open the Accessibility tab to see each violation in context

Reported accessibility violations in these files / stories

Checked tasks have been fixed in #2400

• packages/react/stories/showcase.stories.tsx
  story: Showcase
  violation: Select element must have an accessible name
• packages/react/src/components/form/Combobox/Combobox.stories.tsx
  story: Controlled
  violation: Form elements must have labels
• packages/react/src/components/form/Combobox/Combobox.stories.tsx
  story: ThousandsOfOptions
  violation: Form elements must have labels
• packages/react/src/components/form/Combobox/Combobox.stories.tsx
  story: RemoveAllOptions
  violation: Form elements must have labels
• packages/react/src/components/form/Combobox/Combobox.stories.tsx
  story: WithNumberValues
  violation: Form elements must have labels
• packages/react/src/components/Table/Table.stories.tsx
  story: StickyHeader
  violation: Scrollable region must have keyboard access
• packages/react/src/components/Table/Table.stories.tsx
  story: WithFormElements
  violation: Table header text should not be empty
• packages/react/src/components/Table/Table.stories.tsx
  story: WithFormElements
  violation: Form elements must have labels
• packages/react/src/components/Button/Button.stories.tsx
  story: AsLink
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Tooltip/Tooltip.stories.tsx
  story: DefaultOpen
  violation: Elements must meet minimum color contrast ratio thresholds
• packages/react/src/components/Button/Button.stories.tsx
  story: Icons
  violation: Buttons must have discernible text
• packages/react/src/components/Button/Button.stories.tsx
  story: IconOnly
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Button/Button.stories.tsx
  story: IconsOnlyPrimary
  violation: Buttons must have discernible text
• packages/react/src/components/Button/Button.stories.tsx
  story: IconsOnlyPrimary
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Badge/Badge.stories.tsx
  story: Floating
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Badge/Badge.stories.tsx
  story: CustomPlacement
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Badge/Badge.stories.tsx
  story: Status
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Badge/Badge.stories.tsx
  story: InTabs
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Badge/Badge.stories.tsx
  story: InButton
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Badge/Badge.stories.tsx
  story: InButton
  violation: Buttons must have discernible text
• packages/react/src/components/Alert/Alert.stories.tsx
  story: MedAria
  violation: ARIA role should be appropriate for the element
• packages/react/src/components/ToggleGroup/ToggleGroup.stories.tsx
  story: Kontrollert
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/Tabs/Tabs.stories.tsx
  story: Controlled
  violation: <svg> elements with an img role must have an alternative text
• packages/react/src/components/loaders/Skeleton/Skeleton.stories.tsx
  story: TextExample
  violation: Elements must meet minimum color contrast ratio thresholds
• packages/react/src/components/form/Switch/Switch.stories.tsx
  story: FullWidth
  violation: Elements must meet minimum color contrast ratio thresholds
• packages/react/src/components/form/Switch/Switch.stories.tsx
  story: FullWidthRight
  violation: Elements must meet minimum color contrast ratio thresholds

Violations we will ignore

These violations are examples of invalid usage of components, but these stories only exist to test sizing/alignment, so we don't want to do the work to add correct aria attributes.

• packages/react/stories/testing.stories.tsx
  story: MediumRow
• packages/react/stories/testing.stories.tsx
  story: SmallRow
• packages/react/stories/testing.stories.tsx
  story: LargeRow
• packages/react/stories/testing.stories.tsx
  story: SmallCol
• packages/react/stories/testing.stories.tsx
  story: MediumCol
• packages/react/stories/testing.stories.tsx
  story: LargeCol