feat: refactor RTL modules and utilities for improved consistency and error handling

- Updated license headers to use SPDX format across all RTL files.
- Enhanced error checking in various modules (e.g., tech_ram, tech_regfile, bin2gray, gray2bin, lfsr) to validate parameters and prevent invalid configurations.
- Refactored FIFO implementation to simplify pointer management and ensure proper handling of push/pop operations.
- Introduced new scripts for checking formatting and license headers, ensuring compliance with project standards.
- Added style guidelines to maintain consistent coding practices across the RTL codebase.
- Updated testbench files to include license headers and maintain compatibility with legacy structures.

rtl/cdc/cdc_2phase.sv

@@ -8,6 +8,7 @@
 // this License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
 // specific language governing permissions and limitations under the License.
+// SPDX-License-Identifier: SHL-0.51
 //
 // Fabian Schuiki <fschuiki@iis.ee.ethz.ch>
 //