Phase 1: Implement response transformer, ability to add simple config and validate config expression

[mildronize]

Due to the design spec:

• Ability to config rule of modify response  #2

Store config rule in a data store

• Support in Azure Storage Table (For the first phase, the end user can use [Azure Storage Explorer](https://azure.microsoft.com/en-us/products/storage/storage-explorer) to config it.)

Admin Route

• Serve the affected rules using path /srp (If pass expression evaluation) using [thaitype/data-viewer#6](Provide express middleware as external library data-viewer#6), to show the list for debugg
• Using env variables: SRP_ADMIN_ROOT_PATH : the root path of admin of the reverse proxy, default is /srp

Data Schema for Spy config rules

• ruleName
• upstreamUrl
• path
• condition
  • true / false
• plugin
  • response_transformer
• data
  • Expression syntax for **response_transformer**
    1. <action> = <value>, the value is JSON-compatibility data
    2. <action> = <key> : <value>, the value is JSON-compatibility data
    3. Multiple expression⇒
       1. Ex: <action> = <value> , <action> = <value>
       2. Ex: <action> = <value> , <action> = <key> : <value>
  • Allow Actions
    • replace.status_code
      • replace.status_code=400