Add spellcheck & remediate found spelling issues

[SeanKilleen]

Why:

Closes #23188

What's being changed (if available, include any code snippets, screenshots, or gifs):

• Add GitHub Action that runs cSpell (which the devcontainer already uses as an extension)
• Remediate cSpell findings by fixing issues, adding ignores, or adding words to the dictionary.
• Fix ~20 spelling issues.

Check off the following:

• I have reviewed my changes in staging (look for the "Automatically generated comment" and click the links in the "Preview" column to view your latest changes).
• For content changes, I have completed the self-review checklist.

Notes on Remediations

• In some cases, I noticed issues raised because liquid syntax was missing a space at the end. In those cases, I fixed the liquid syntax
• In cases where the cSpell finding was related to terminology within the body of a document, I added back-ticks in cases where I thought that choice would be aligned with the markdown standards.
• In cases where words were used in one article only, I added cSpell:ignore lines to the frontmatter
• Oftentimes I added words to the cSpell dictionary to remediate.
• cSpell uses en-US by default; in some cases I changed words to conform to that standard (e.g. behaviour to behavior).

Remaining Tasks

Surfaced by the build system that I can see.

• Reconcile cSpell's frontmatter ignore syntax with the link-check that is failing due to invalid frontmatter
• Run prettier on the spellcheck.yml file
• Understand why unit tests are failing on the contents of the spellcheck workflow and remediate
• Remove workflow entirely if it's not allowed (hopefully not the case)
• Squash changes (if maintainers won't be doing that)

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
.devcontainer/**
.github/actions-scripts/**
.github/workflows/**
.github/CODEOWNERS
assets/fonts/**
data/graphql/**
Dockerfile*
src/**
lib/redirects/**
package*.json
scripts/**
content/actions/deployment/security-hardening-your-deployments/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
.devcontainer/**
.github/actions-scripts/**
.github/workflows/**
.github/CODEOWNERS
assets/fonts/**
data/graphql/**
Dockerfile*
src/**
lib/redirects/**
package*.json
scripts/**
content/actions/deployment/security-hardening-your-deployments/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
.devcontainer/**
.github/actions-scripts/**
.github/workflows/**
.github/CODEOWNERS
assets/fonts/**
data/graphql/**
Dockerfile*
src/**
lib/redirects/**
package*.json
scripts/**
content/actions/deployment/security-hardening-your-deployments/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
.devcontainer/**
.github/actions-scripts/**
.github/workflows/**
.github/CODEOWNERS
assets/fonts/**
data/graphql/**
Dockerfile*
src/**
lib/redirects/**
package*.json
scripts/**
content/actions/deployment/security-hardening-your-deployments/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[janiceilene]

Thanks again for all the amazing work and inspiration @SeanKilleen 😍 We're still working on an internal solution, so I'm going to close this up in the meantime 💖

[SeanKilleen]

@janiceilene I had kept this open in the hopes to learn more about that solution when it happened. I didn't mind submitting fixes in the meantime and this was my primary mechanism to do so.

Either way, glad to have been able to make a contribution. Good luck with it!

[janiceilene]

@SeanKilleen Good call out, thank you! We just added a note to our plans to make sure we open a discussion in this repo when we launch ✨