Add datadog tracing

[mprince]

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

feature: add datadog tracing

• What is the current behavior? (You can also link to an open issue here)

No monitoring tools availble for leek itself.

• What is the new behavior (if this is a feature change)?

This will enable users who are using datadog for their monitoring to run leek with apm tracing.

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

No

• Other information: