GH-4950 LMDB: extensible ID scheme

[kenwenzel]

Implement an extensible ID scheme for the LmdbStore that also allows to embed values into IDs.

GitHub issue resolved: #4950

Briefly describe the changes proposed in this PR:

Use a binary encoding for IDs that allows to represent the value type, if the value itself is embedded within the id and the embedded value itself.

---

PR Author Checklist (see the contributor guidelines for more details):

• my pull request is self-contained
• I've added tests for the changes I made
• I've applied code formatting (you can use mvn process-resources to format from the command line)
• I've squashed my commits where necessary
• every commit message starts with the issue number (GH-xxxx) followed by a meaningful description of the change

[hmottestad]

The failing integration tests: It's a test that is marked as disabled, but has somehow started to run again. Not sure how that happened.