feat(manager/mise): add support for neo4j

[mnm364]

Changes

Adds neo4j (Neo4j) to the set of mise tools renovate can manage. Neo4j is a high-performance, native graph database with full ACID transactions, the Cypher query language, and a flexible property graph model.

Versions are sourced from Maven Central (`org.neo4j:neo4j`), which is comprehensive — its `maven-metadata.xml` lists every published release back to 1.2.M01 and currently includes the latest `2026.04.0`. `MavenDatasource` is added to the mise manager's `core` supported datasources so registry tools (like neo4j) can use it.

This pairs with jdx/mise#9525, which adds the corresponding `registry/neo4j.toml` to the mise registry. After both land, users can drop manual `# renovate:` overrides and rely on the registry name:

```toml
[tools]
neo4j = "2026.04.0"
```

Context

• This doesn't close an Issue, but I accept the risk that this PR may be closed if maintainers disagree with its opening or implementation

AI assistance disclosure

• Yes — substantive assistance (AI-generated non‑trivial portions of code, tests, and documentation).

Documentation (please check one with an [x])

• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Newly added/modified unit tests

[viceice]

closing in favor of

• feat(data): automatic update of static data #43079