* Implement mechanism to apply custom api path to the sleuth server baseUrl.
This comes in handy when another monitoring tool is being used, for instance new relic, which doesn't not require path in its tracing api.
* Fix up documentation on the ZipkinProperties
* Update the main documentation for api path
* Add missing comma
# Modules
* New modules: `spring-cloud-sleuth-autoconfigure`, `spring-cloud-sleuth-api`, `spring-cloud-sleuth-instrumentation`
`spring-cloud-sleuth-core` removed and changed to `spring-cloud-sleuth-instrumentation` & `spring-cloud-sleuth-api`
* Removed `spring-cloud-starter-sleuth-otel`
To add OpenTelemetry support you need to add `spring-cloud-starter-sleuth` (adds Brave by default), exclude Brave and add `spring-cloud-sleuth-otel` dependency
* Except for the tests, `spring-cloud-sleuth-autoconfigure` is the only module that can have access to `@Configuration`, `@ConfigurationProperties` classes.
Tests have been added to ensure such separation.
## Package moving
* `org.springframework.cloud.sleuth.api` -> `org.springframework.cloud.sleuth`
* `org.springframework.cloud.sleuth.brave.autoconfig` -> `org.springframework.cloud.sleuth.autoconfig.brave`
* `org.springframework.cloud.sleuth.otel.autoconfig` -> `org.springframework.cloud.sleuth.autoconfig.otel`
* `org.springframework.cloud.sleuth` -> `org.springframework.cloud.sleuth`
* Instrumentation: `org.springframework.cloud.sleuth.annotation` -> `org.springframework.cloud.sleuth.instrument.annotation`
* All the autoconfiguration classes were moved under `org.springframework.cloud/sleuth.autoconfig` package
## Global class modifications
* Any class registered as a bean is now public
## Classes
* `RateLimitingSampler` constructor changed
* Merged a lot of auto configuration classes into one (e.g. `BraveAutoConfiguration` now imports various other configurations)
* Renamed `TraceBraveAutoConfiguration` to `BraveAutoConfiguration`
* Renamed `TraceOtelAutoConfiguration` to `OtelAutoConfiguration`
* Removed all `NoOp` implementations of the API
