thunderbolt: test: Add KUnit tests for property parser bounds checks

thunderbolt: test: Add KUnit tests for property parser bounds checks

Add regression tests for the zero-length entry and root directory
bounds fixes:

- tb_test_property_parse_zero_length: TEXT entry with length 0
  must be rejected by the validator.

- tb_test_property_parse_rootdir_overflow: root directory whose
  content_offset + content_len exceeds block_len must be rejected.

Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>