Ready to release 0.3.0

[KeRan213539]

The branch of 0.2.0 is master-0.2.0. If your PR is to solve the problem of 0.2.0, please submit the PR to it.
Please do not create a Pull Request without creating an issue first.

What is the purpose of the change

Ready to release 0.3.0

Brief changelog

1. Modified version to 0.3.0
2. Adjust POM dependencies and use Dubbo's dependency version control
3. Add display of version on UI
4. Add 0.3.0 docker related scripts

Verifying this change

XXXX

Follow this checklist to help us incorporate your contribution quickly and easily:

• Make sure there is a Github issue filed for the change (usually before you start working on it). Trivial changes like typos do not require a Github issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Format the pull request title like [ISSUE #123] Fix UnknownException when host config not exist. Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist.
• Run `mvn clean compile --batch-mode -DskipTests=false -Dcheckstyle.skip=false -Drat.skip=false -Dmaven.javadoc.skip=true to make sure basic checks pass.

[codecov-commenter]

Codecov Report

Merging #797 (e280b1b) into develop (021c3f5) will decrease coverage by 0.09%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             develop     #797      +/-   ##
=============================================
- Coverage      20.36%   20.26%   -0.10%     
+ Complexity       331      326       -5     
=============================================
  Files             97       97              
  Lines           3885     3889       +4     
  Branches         616      616              
=============================================
- Hits             791      788       -3     
- Misses          3018     3023       +5     
- Partials          76       78       +2     

Flag	Coverage Δ
unit	20.26% <ø> (-0.10%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...apache/dubbo/admin/service/RegistryServerSync.java	83.58% <0.00%> (-10.45%)	⬇️
...va/org/apache/dubbo/admin/config/ConfigCenter.java	88.13% <0.00%> (+0.86%)	⬆️

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[htynkn]

LGTM

[haoyann]

LGTM