feat: use Lua's __index to mock all of the share dict

[membphis]

• Why do you submit this issue?
• Feature or performance improvement

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Question

• What do you want to know?

original comment: https://github.com/apache/apisix-dashboard/pull/651/files#r516339002

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Requirements or improvement

• Please describe your requirements or improvement suggestions.

__index can mock all of the share dicts, even we can use it to mock all of the API in ngx.

[juzhiyuan]

done?

[juzhiyuan]

cc @starsz

[starsz]

Please assign it to me. I will improve the schema-sync.lua.

Releated: #1237.

[nic-chen]

we don't need the tool schema-sync now, we could use APISIX controlAPI to export schema.
we only need to update doc about sync schema here.

[nic-chen]

it's same with #1237 , we could close this now.

[juzhiyuan]

@nic-chen Please remove any related text from this repo if needed

[nic-chen]

@nic-chen Please remove any related text from this repo if needed

sure, we will update the doc, and track it in #1237