tracepoint probe refactoring: Move provider name to provider descriptor

The provider name is currently repeated for each event name as:

  <provider name>:<event name>

This repetition requires that each event embeds the provider name within
its own name.

Use this ABI break to clean this up: instead, each event descriptor has
a pointer to its probe descriptor, and each probe descriptor has a
provider name.

Implement name size validation and event name formatting internal
helpers, and use them across the tracer.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ief8a4696a2030bf3b9c785b8422f382079c6bf06