[Addon] Chartmuseum add a cache refresh option #751

[oanasc]

Description of your changes

Add an option to change the default configuration of the default cache refresh interval, the default is causing us to have stale charts and failing releases.

How has this code been tested?

Checklist

I have:

• Title of the PR starts with type (e.g. [Addon] , [example] or [Doc]).
• Updated/Added any relevant documentation and examples.
• New addon should be put in experimental.
• Update addon should modify the version in metadata.yaml to generate a new version.

Verified Addon promotion rules

If this pr wants to promote an experimental addon to verified, you must check whether meet these conditions too:

• This addon must be tested by addon's e2e-test to guarantee this addon can be enabled successfully.
• This addon must have some basic but necessary information.
  • An accessible icon url and source url defined in addon's metadata.yaml.
  • A detail introduction include a basic example about how to use and what's the benefit of this addon in README.md.
  • Also provide an introduction in KubeVela documentation.
  • It's more likely to be accepted if useful examples provided in example dir.

[oanasc]

@charlie0129 Trying this again (my rebase broke a cardinal rule - rebased an empty commit) and have reopened as a fresh branch/PR. Thanks

[charlie0129]

LGTM