Use string interpolation when possible

Created by: uwx

Summary

Refactors the lib's code to use string interpolation instead of calls to string.Concat.

Details

This should not affect lib functionality, it is a purely under-the-hood change.

If performance is a concern, please keep in mind that the compiled calls to string.Format are very, very likely sub-1ms and are completely negligible compared to any of the more heavyset lib operations, like sending a request or starting a task.

Changes proposed

• Use string interpolation instead of string.Format in lib code

Notes

This is the first in a series of three PRs with small improvements to lib internals, with the intention of making code more readable.