test: cover versionbits deployment info names

[iamdinhthuan]

Summary

• add a focused deploymentinfo_tests unit-test suite
• assert every VersionBitsDeploymentInfo entry has a non-null, non-empty name
• compare DeploymentName() against the metadata table so missing versionbits entries are caught before RPC code can construct invalid strings

Context

This adds regression coverage for the class of issue discussed in #123, where a missing versionbits deployment name could make getblocktemplate fail with basic_string::_M_construct null not valid.

Verification

• RED check: temporarily set taproot_discarded's deployment name to nullptr; LD_LIBRARY_PATH=/home/thuan/miniconda3/envs/py311/lib src/test/test_BGL --run_test=deploymentinfo_tests failed with missing deployment name at index 1
• make -j2 -C src test/test_BGL
• LD_LIBRARY_PATH=/home/thuan/miniconda3/envs/py311/lib src/test/test_BGL --run_test=deploymentinfo_tests -> No errors detected
• git diff --cached --check

Bounty / payout

Submitting for the open Bitgesell PR bounty program (#32, #39, #81) if maintainers consider this eligible.

Payout if approved: USDT or USDC SPL on Solana: 6mL4QQwcwLmb9UX1PjHtRSQ8J3HazCeVSDdZdDVQGXJj.