declarative config: early init and property mapping

[zeitlinger]

Fixes #14133
Fixes #14132
Fixes #14160

Integration test already existed before:

opentelemetry-java-instrumentation/instrumentation/methods/javaagent/build.gradle.kts

Lines 22 to 36 in 4251217

	testing {
	suites {
	val declarativeConfigTest by registering(JvmTestSuite::class) {
	targets {
	all {
	testTask.configure {
	jvmArgs(
	"-Dotel.experimental.config.file=$projectDir/src/declarativeConfigTest/resources/declarative-config.yaml"
	)
	}
	}
	}
	}
	}
	}

[zeitlinger]

@laurit @trask please have a look 😄

I will create a bunch of follow up tasks to not make this PR bigger.

[zeitlinger]

We may need to rearrange the code to install the early instrumentations before configuration is available to ensure that we can transform the classes before they are loaded.

This still leaves "otel.javaagent.enabled" - which promises not to touch anything if the value is false.

[zeitlinger]

The problem with logging is that currently it should be configured before anything is logged

https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfiguration.java doesn't log for the method that we call - but jackson can throw exceptions (which I can buffer like ConfigurationFile)

[zeitlinger]

Reading the declarative config is going to pull in a bunch of classes which could load the classes we wish to transform

How can we find out if that's the case? E.g. a tool to compare loaded classes against what we want to transform.

[zeitlinger]

The problem with logging is that currently it should be configured before anything is logged

https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfiguration.java doesn't log for the method that we call - but jackson can throw exceptions (which I can buffer like ConfigurationFile)

extracted ErrorBuffer: https://github.com/zeitlinger/opentelemetry-java-instrumentation/blob/eb8ee1978206d602db9e07b02e09b36e01d3cad3/javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/config/ErrorBuffer.java

[zeitlinger]

@laurit please have a look 😄

[otelbot-java-instrumentation]

🔧 The result from spotlessApply was committed to the PR branch.

[zeitlinger]

@laurit please check again