add codespell action

[t-bltg]

Description

Add a codespell action based on codespell, per #4522 (comment).

This should be low noise (hint only):

• only on PRs;
• should only warn, not error CI;
• shouldn't add noise to code annotations (such as the one generated by codecov).

Type of change

• add CI check;
• correct another bunch of spelling errors (more controversial though ? e.g. re-use -> reuse);
• some of the remaining "spelling errors" are now related to the pending PR rename tesselation to tessellation JuliaGeometry/GeometryBasics.jl#227.

[t-bltg]

Remaining false-positives, comments are welcome:

[ffreyer]

I cleaned up a couple of those warnings. The remaining ones are:

• local variables with shortened names (bu, te, ser, jus)
• Tesselation
• OT is short for ObservableType I believe

[ffreyer]

Just to keep you updated - I talked with Simon and Julius and we're doing the Tesselation -> Tessellation change with the GeometryBasics refactor in the next release. I did the renaming for that in #4564 and merged it into #4477