Fix YAML properties with hyphens cause Build error

[mohamedsalem401]

For issue #636:

• After debugging, I discovered that MDX-Remote is the cause of this failure.
• It seems to use YAML properties within a new function(arg1, arg2) format, where each argument corresponds to a YAML property. This requires the properties to be in a format that's a valid variable name (i.e., no spaces or strange characters).
• MDX-Remote replaces variables in the content body with these YAML properties, like so:

---
my_name: "Mohamed"
---
My name is {my_name} // the output will be My name is Mohamed

• This pull request replaces all hyphens/other characters in the YAML properties with underscores.
• However, it doesn't handle cases where a user employs the YAML property as a variable value. Since this PR doesn't modify the content of the file itself (i.e., it won't change hyphens in the body {my-name} to underscores {my_name}), this scenario remains unaddressed.

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Name	Status	Preview	Updated (UTC)
flowershow-ssr-r2	✅ Ready (Inspect)	Visit Preview	Apr 28, 2024 7:58pm

[rufuspollock]

I'm not clear if this actually changes the file before processing by our mdx pipeline which will cause a bunch of issues - where does the modification happen?