Wasm configuration v2

[eguzki]

What

Fixes #35 Depends on https://github.com/Kuadrant/wasm-test-framework/pull/1 for e2e tests to pass

Example to illustrate the new wasm shim configuration struct

failureMode: deny
rateLimitPolicies:
  - name: rlp-ns-A/rlp-name-A
    domain: rlp-ns-A/rlp-name-A
    service: rate-limit-cluster
    hostnames: ["*.toystore.com"]
    rules:   
      - conditions:      
        - allOf:
          - selector: <value>
            operator: <value>
            value: <value>
          - selector: <value>
            operator: <value>
            value: <value>
        - allOf:
          - selector: <value>
            operator: <value>
            value: <value>
          - selector: <value>
            operator: <value>
            value: <value>
        data:
        - selector:
            selector: <value>       # Any attribute from a well-known specification TBD ([ref](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/advanced/attributes#arch-overview-request-attributes))
            key: <value>             # Optional. If not set it defaults to `selector` field value as the descriptor key.
            default: <value>        # Optional. An optional value to use if metadata_key is empty. If not set and no value is present under the metadata_key then no descriptor is generated.
        - static:   
            key: <value>             # Required
            value: <value>          # Required

• Upgrade proxy-wasm to 0.2.1. Hit this issue https://github.com/proxy-wasm/proxy-wasm-rust-sdk/pull/154 and latest release includes the fix

TODO:

• [X] rate limit Wasm shim V2 new configuration
• [x] matches condition selector operator implementation
• [x] Tokenize selector fields with escape char \. Example: Input: this.is.a.exam\.ple -> Retuns: ["this", "is", "a", "exam.ple"]. Some path segments include dot . char in them. For instance envoy filter names: envoy.filters.http.header_to_metadata
• [ ] ~Support data types other than string from envoy attributes https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/advanced/attributes~ (opened issue https://github.com/Kuadrant/wasm-shim/issues/38 for that)
• [x] e2e tests
• [x] Doc

[guicassolato]

LGTM so far, @eguzki. Nice job!

[eguzki]

@guicassolato ready for another review as you requested changes

[eguzki]

green :partying_face: