Implement CSS-only input toggling, refactor related forms

UX/Translation changes:

- new teams: remove redundant tooltips that don't add meaningful information
  - move general information to table fieldset
- new teams: rename "general" to "custom" access for clarity
- new teams: show labels beside options on mobile

Accessibility:

- semantic form elements allow easier navigation (fieldset, mostly)
- improve better labelling of new teams table
- fix accessibility scan issues
- TODO: the parts that "disable" form elements were not yet touched and
  are not really accessible to screenreaders

Technical:

- replace two JavaScript solutions with one CSS standard
- implement a simpler grid (.simple-grid)
- simplify markup
- remove some webhook settings specific CSS

Testing:

- check more form content for accessibility issues
- but exclude tooltips from the scan :(
- reuse existing form tests from previous PR

tests/e2e/org-settings.test.e2e.js

@@ -14,12 +14,11 @@ test('org team settings', async ({browser}, workerInfo) => {
   await expect(response?.status()).toBe(200);
 
   await page.locator('input[name="permission"][value="admin"]').click();
-  await expect(page.locator('.team-units')).toBeHidden();
-
-  // we are validating the form here, because the now hidden part has accessibility issues anyway
-  // this should be moved up or down once they are fixed.
-  await validate_form({page});
+  await expect(page.locator('.hide-unless-checked')).toBeHidden();
 
   await page.locator('input[name="permission"][value="read"]').click();
-  await expect(page.locator('.team-units')).toBeVisible();
+  await expect(page.locator('.hide-unless-checked')).toBeVisible();
+
+  // we are validating the form here to include the part that could be hidden
+  await validate_form({page});
 });