Generate executable releases

[brunoluiz]

The PGO optimisation seems to work okay, but if the go mod cache is generated in jobs where it is not included, it is not properly cached. With that, on every run, PGO needs to have its dependencies downloaded + compiled during CI. This can add around 20 seconds of build time.

An example of that is when you have the following flow:

                      ┌────────────────────┐                                
                      │                    │                                
                      │ go mod cache warm                                   
                      │                    │                                
             ┌────────┴─────────┬──────────┴─────────┐                      
             │                  │                    │                      
             │                  │                    │                      
             │                  │                    │                      
             │                  │                    │                      
             │                  │                    │                      
     ┌───────▼──────┐     ┌─────▼───────┐     ┌──────▼──────┐               
     │              │     │             │     │             │               
     │     test     │     │    build    │     │    lint     │               
     │              │     │             │     │             │               
     └──────────────┘     └─────────────┘     └─────────────┘               

In this case, when the go mod cache warm runs, it doesn't save the datadog-pgo deps at all. Besides that, there is the build time, as mentioned.

Ideally, this could be solved by either:

1. Provided as a release, where developers can fetch using releases API
2. Provided as a Github Action, where a simple setup-datadog-pgo would do all the heavy lifting (download release etc)