Inclusive language update (allowlist/denylist). #4

What?

I've gone through the code and replaced the following terms:

'blacklist' -> 'denylist'
'whitelist' -> 'allowlist'

Why?

See Issue#2 - it boils down to an attempt in reducing harmful and exclusionary language.
The Inclusive Naming org gives a good rationale for updating these words specifically.

How?

Ran a sed command to recursively find/replace within the code.

I then manually reviewed the changes, and re-aligned certain parts of code.

Testing?

I've successfully run go build (go-version: 1.20), which appears to run OK.

Anything Else?

This PR does introduce a functional change, the flag from -blacklist to -denylist.
The README.md and other files are already updated to reflect that, but details of this change may need adding to the release notes.

This looks great, thanks!