Add Ssdbltrp and Smdbltrp extension tests

[ved-rivos]

Description

Add tests for Ssdbltrp and Smdbltrp extensions
Parts of Smdbltrp to redirect to RNMI handler is not included pending merge of Smrnmi extension PR into Sail

Related Issues

N/A

Ratified/Unratified Extensions

• Ratified
• Unratified

List Extensions

Ssdbltrp, Smdbltrp - https://github.com/riscv/riscv-double-trap

Reference Model Used

• SAIL
• Spike
• Other - < SPECIFY HERE >

Mandatory Checklist:

• All tests are compliant with the test-format spec present in this repo ?
• Ran the new tests on RISCOF with SAIL/Spike as reference model successfully ?
• Ran the new tests on RISCOF in coverage mode
• Link to Google-Drive folder containing the new coverage reports (See this for more info): < SPECIFY HERE >
• Link to PR in RISCV-ISAC from which the reports were generated : < SPECIFY HERE >
• Changelog entry created with a minor patch

Optional Checklist:

• RISCV-V CTG PR link if tests were generated using it : < SPECIFY HERE >
• Were the tests hand-written/modified ?
• Have you run these on any hard DUT model ? Please specify name and provide link if possible in the description
• If you have modified arch_test.h Please provide a detailed description of the changes in the Description section above.