core(network-request): cleanup DevTools property names

[patrickhulce]

https://www.youtube.com/watch?v=WJ9uhDzN-rA

• Remove all the _ from the network request properties
• Updates our existing network record fixtures to have no _
• Removes functions that didn't need to be functions
• Removes unused fixture and computed artifact
• Removes web-inspector.d.ts typings

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Split into 2 commits for easier (maybe?) reviewing, 1 removes the underscores, the next converts the functions and removes the web inspector types

[patrickhulce]

@brendankenny I know this is big, but it can conflict with stuff real soon if we make too many changes, so quick look would be nice :) (most of the line volume changes are to fixtures)

[brendankenny]

LGTM!
:long_cat: