Add Real-time Linux Analysis tool (rtla) to linux-tools

[Impact]

The **rtla** is a meta-tool that includes a set of commands that aims to analyze the real-time properties of Linux.

Considering the latest "low-latency" capabilities acquired by the generic kernel and also considering the recent trend in Ubuntu to focus on performance and observability (see for example https://ubuntu.com/blog/ubuntu-performance-engineering-with-frame-pointers-by-default), it makes sense to provide more tools that can help to analyze timing/responsive performance, such as rtla.

[Test case]

Simple rtla usage to measure the timer irq / timer thread latency:

 $ sudo rtla timerlat

[Fix]

Enable the build of the rtla binary during the kernel build and ship it with linux-tools.

[Regression potential]

The only potential regression is an increased amount of size in the linux-tools package, due to the extra binary.

However, the binary itself is really small, the kernel already has all the required capabilities enabled and we don't need to introduce any additional user-space dependency, therefore such extra space is expected to be minimal.