Simplify creating test data for profiles support

[rockdaboot]

Component(s)

No response

Is your feature request related to a problem? Please describe.

Creating instances of pprofile.Profile for testing profiles related code is currently tedious and unnecessary hard to read. Example
Too many details of the protobuf definition are exposed and expected to be known to the writers of tests that involve profiles.

Every component that needs to create pprofile.Profile items to test with would benefit.

Describe the solution you'd like

We could use Go types for the definition of test cases without exposing protocol internals (for example, how de-duplication of items is done), and a transformation function that transforms the test case into pprofile.Profile.

Example

testcase

	tp := &testProfile{
		sampleType: []testValueType{
			{
				typ:                    "samples",
				unit:                   "count",
				aggregationTemporality: pprofile.AggregationTemporalityDelta,
			},
		},
		sample: []testSample{
			{
				timestamp: 42,
				link: testLink{
					traceID: [16]byte{0x01, 0x02},
					spanID:  [16]byte{0x03, 0x04},
				},
				value: 1,
				locations: []testLocation{
					{
						mapping: &testMapping{
							memoryStart: 0x1000,
							memoryLimit: 0x2000,
							fileOffset:  0x3000,
							fileName:    "file1",
							attributes: []testAttribute{
								{
									key:   "mapping.attribute.key",
									value: "mapping.attribute.value",
								},
							},
							hasFunctions:    true,
							hasFileNames:    true,
							hasLineNumbers:  true,
							hasInlineFrames: true,
						},
						address: 0x1000,
						line: []testLine{
							{
								line:   1,
								column: 2,
								function: testFunction{
									name:       "func1",
									systemName: "system1",
									fileName:   "file1",
									startLine:  1,
								},
							},
						},
						isFolded: true,
						attributes: []testAttribute{
							{
								key:   "location.attribute.key",
								value: "location.attribute.value",
							},
						},
					},
				},
				attributes: []testAttribute{
					{
						key:   "sample.attribute.key",
						value: "sample.attribute.value",
					},
				},
			},
		},
		timeNanos:     42,
		durationNanos: 84,
		periodType: testValueType{
			typ:  "cpu",
			unit: "nanoseconds",
		},
		period:  1e9 / 20,
		comment: []string{"comment1", "comment2"},
		defaultSampleType: testValueType{
			typ:  "samples",
			unit: "count",
		},
		profileID:              [16]byte{0x05, 0x06},
		droppedAttributesCount: 1,
		originalPayloadFormat:  "payloadFormat",
		originalPayload:        []byte{0x07, 0x08},
		attributes: []testAttribute{
			{
				key:   "profile.attribute.key",
				value: "profile.attribute.value",
			},
		},
	}

	pp, err := td.ToPProfile()

Describe alternatives you've considered

JSON definition: too error-prone, needs additional dependencies
Pre-recorded protobuf files: Requires extra amount of work, can't easily define corner-cases

Additional context

No response

[rockdaboot]

@atoulme Do you mind to assign the issue to me? I already have code locally.

[dmathieu]

This has been moved to collector core. However, I'm not sure that's appropriate.

The intent for these helpers it very similar to what telemetrygen does, as in generate fake data that can be used to test plugins that manipulate profiling data.
Pdata is indeed meant to manipulate profiling data, but at runtime. More advanced generation of test data for other profiles do not reside in there.

So I think this should be moved back to the contrib repository, as this is not in the pdata area.

[rockdaboot]

I followed the suggestion of @dmathieu and created the PR in collector-contrib.

@atoulme Please see Damien's comment above.