feat: add triangle latency summand

[roertbb]

What was done in this PR:

• Added triangle summands.

Additionally:

• Adjusted the order of passing args to some assertions to match naming from https://pkg.go.dev/github.com/stretchr/testify/assert#Equal (expected is passed first, and actual value is the last arg)
• Fixed typo sawAmplitute -> sawAmplitude

Resolves #19

[kffl]

This PR adds triangle and square latency summands. After submitting the PR I've noticed that someone already submitted a PR for square latency summand in #17. I'll wait until it's merged and adjust my changes to add triangle latency summand only. Will it work for us, wdyt?

Thank you for implementing both of them! #17 just got merged

Good catch on that sawAmplitute typo. Since it is an exported field in an exported struct LatencyCfg and I'm rather strict about adhering to SemVer, it seems that we are going to arrive at v1 rather quickly. Putting this fix aside, I have already planned altering the proxy Start() and Stop() methods to make them more intuitive, so the timing for a major version bump is pretty great.

[kffl]

Thanks a lot for taking the time to prepare this PR. I've included my remarks regarding potential simplification of the triangle wave function. Let me know if you would like to refactor it. If not - no worries, this is by no means obligatory.

[kffl]

LGTM, thanks a lot for introducing the changes.