Merge branch '513631-convert-webhooks-settings-page-to-vue-and-rearrange-url-masking' into 'master' 

Simplify URL masking UI for project and group webhooks

See merge request !189235



Merged-by: Andrew Fontaine <afontaine@gitlab.com>
Approved-by: Chad Lavimoniere <clavimoniere@gitlab.com>
Approved-by: Ashraf Khamis <akhamis@gitlab.com>
Approved-by: Shane Maglangit <smaglangit@gitlab.com>
Approved-by: Andrew Fontaine <afontaine@gitlab.com>
Reviewed-by: Justin Ho Tuan Duong <hduong@gitlab.com>
Reviewed-by: Ashraf Khamis <akhamis@gitlab.com>
Reviewed-by: Shane Maglangit <smaglangit@gitlab.com>
Co-authored-by: Justin Ho Tuan Duong <hduong@gitlab.com>