Rename enableHttpProxyingRequest to enableProxyingHttpRequest

[anthonychu]

Purpose

Fix bug in host.json. Updating property name to match schema: https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/host.json#L1074-L1078

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

[lilyjma]

Thanks for calling it out! Merging.