Following the `getByText()` and other methods:
- By default, matching is substring and case-insensitive. Before, it was
only case-insensitive, but not substring.
- With new option `exact: true`, matching is full string and
case-sensitive.
- Matching always normalizes whitespace.
- Codegen generates `exact: false` by default.
- `internal:role` treats `[name="foo"i]` as non-exact match.
Various fixes:
- Updated `getByRole` docs to match the reality.
- Locator generator edge cases.
- prefer `role=checkbox` over `input[type=checkbox]`
- prefer `#id` over `input[type=checkbox]` and `role=checkbox`
- prefer `text=foo` over `internal:has-text=foo`
- ignore `none` and `presentation` roles
- remove non-strict support
