fix: use proper field names in cacheable codecs

[anthony-swirldslabs]

Description:
Fixing a small bug in the pbj.cacheable implementation where embedded hashCode() and equals() bodies used incorrect field names to refer to local temp_ variables. They used camelCase names while the temp_ fields use original protobuf names, which may be snake_case.

Test models are updated to verify this fix.

Related issue(s):

Fixes #844

Notes for reviewer:
All tests should pass.

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[github-actions]

JUnit Test Report

   521 files  ±0     521 suites  ±0   27s ⏱️ -1s
 1 537 tests ±0   1 533 ✅ ±0   4 💤 ±0  0 ❌ ±0 
10 755 runs  ±0  10 727 ✅ ±0  28 💤 ±0  0 ❌ ±0 

Results for commit 7265da3. ± Comparison against base commit f2a1e09.

[github-actions]

Integration Test Report

    428 files  + 2      428 suites  +2   18m 39s ⏱️ - 2m 50s
115 048 tests +18  115 048 ✅ +18  0 💤 ±0  0 ❌ ±0 
115 292 runs  +18  115 292 ✅ +18  0 💤 ±0  0 ❌ ±0 

Results for commit 7265da3. ± Comparison against base commit f2a1e09.

This pull request removes 2 and adds 20 tests. Note that renamed tests count towards both.

com.hedera.pbj.integration.test.ParserNeverWrapsTest ‑ [1] com.hedera.pbj.integration.test.ParserNeverWrapsTest$$Lambda/0x0000000032bf0b18@52388384
com.hedera.pbj.integration.test.ParserNeverWrapsTest ‑ [2] com.hedera.pbj.integration.test.ParserNeverWrapsTest$$Lambda/0x0000000032bf0d60@177c38c5

com.hedera.pbj.integration.test.ParserNeverWrapsTest ‑ [1] com.hedera.pbj.integration.test.ParserNeverWrapsTest$$Lambda/0x000000007cc8e310@7774060f
com.hedera.pbj.integration.test.ParserNeverWrapsTest ‑ [2] com.hedera.pbj.integration.test.ParserNeverWrapsTest$$Lambda/0x000000007cc8e558@58fc8272
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ [1] NoToStringWrapper{com.hedera.pbj.test.proto.pbj.CacheableNftID}
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ [2] NoToStringWrapper{com.hedera.pbj.test.proto.pbj.CacheableNftID}
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ [3] NoToStringWrapper{com.hedera.pbj.test.proto.pbj.CacheableNftID}
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ [4] NoToStringWrapper{com.hedera.pbj.test.proto.pbj.CacheableNftID}
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ [5] NoToStringWrapper{com.hedera.pbj.test.proto.pbj.CacheableNftID}
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ [6] NoToStringWrapper{com.hedera.pbj.test.proto.pbj.CacheableNftID}
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ [7] NoToStringWrapper{com.hedera.pbj.test.proto.pbj.CacheableNftID}
com.hedera.pbj.test.proto.pbj.tests.CacheableNftIDTest ‑ testCodecGetDefaultValueMethod()
…