[Summary] Preparations for Releasing HugeGraph 1.7 Version

# TODOs

> Legecies of [1.5 version](https://github.com/apache/incubator-hugegraph/issues/2575)

- [x] PD/Store related doc transfer (to Wiki/Website) https://github.com/apache/incubator-hugegraph-doc/issues/398
- https://github.com/apache/incubator-hugegraph-doc/pull/402
- [x] remove useless files
- [x] verify-license.json
- [x] hugegraph-pd/hg-pd-dist/src/assembly/static/conf/verify-license.json
- https://github.com/apache/incubator-hugegraph/pull/2681
- [ ] ci
- [ ] merge Hstore CI with server ci
- https://github.com/apache/incubator-hugegraph/pull/2789
- [x] remove the compatible code for Java8 / legacy code https://github.com/apache/incubator-hugegraph/issues/2499
- [x] AuthServer/HugeSecurityManager (remove the [Reflection](https://github.com/apache/incubator-hugegraph/blob/master/hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/util/Reflection.java) code)
- https://github.com/apache/incubator-hugegraph/pull/2792
- [x] Disable legacy master-worker mechanism in multi-server @shirleyStorage
- [ ] pd-store docker:
- [ ] url redirection
- [ ] README

> New tasks in 1.7 version

- [x] Remove unnecessary backend code

- https://github.com/apache/incubator-hugegraph/pull/2746

- [x] update [toolchain](https://github.com/apache/incubator-hugegraph-toolchain) to new version
- [x] https://github.com/apache/incubator-hugegraph-toolchain/pull/633
- [x] https://github.com/apache/incubator-hugegraph-toolchain/pull/632
- [x] support graphspace in server
- [x] JRAFT Leader Preemption and Hessian Deserialization Vulnerabilities
- [x] further migration from internal 3.7/4.0
> Main PR: https://github.com/apache/incubator-hugegraph/pull/2889