Head sampling crd

[tamirdavid1]

I've added @RonFed CRD additions for Head-sampling + change in the relevant places in the code.

[blumamir]

LGTM.
added few nit suggestions about updating someplace to the new names, and consider removing the contains operand for now, as it might get us into problems with eBPF implementation which we can postpone

[edeNFed]

Great job @tamirdavid1
A few comments on naming (nothing really important, feel free to skip all of them):

• .spec.config and .spec.sdkConfigs is confusing. if I understand correctly, one is for sampling and the other is for dynamic instrumentation, so the names should reflect that (sampling/dynamicAttributes/etc)
• All the nested objects are fields in InstrumentationConfig object, I think we can drop the word instrumentation in multiple places in the json fields as it clear that everything is related to instrumentation.
• operandsdoes not make it clear that there is an AND between all of them and that all should return true in order to pass. Maybe we can give it a better name to explain this behavior

Another thing to consider:
I see both .spec.config and .spec.sdkConfigs eventually point to a list of target libraries,
Would it make more sense to unify them both and make the libraries the root object?
Maybe something like:

spec:
    runtimeDetailsInvalidated: false
    configs:
        - name: "net/http"
          traceConfig:
              enbaled: true
          headSampling:
              fallbackFraction: 0.4
              rules:
                  - fraction: 1
                    operands:
                        - key: "http.method"
                          operation: "equal"
                          value: "POST"
          dynamicAttributes:
              - spanKind: "server"
                optionValueBoolean: true
                optionKey: "http.request.body"
    global:
        headSampling:
            fallbackFraction: 0.9

It is a big change and I am not sure how much value it adds, but maybe now is a good time to do it if you find it valuable. (cc @blumamir @RonFed )