Change "Feature Policy" references to "Permission Policy"

[jpmedley]

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Page Affected:

.//updates/2017/09/sensors-for-the-web.md
.//updates/2017/09/autoplay-policy-changes.md
.//updates/2019/04/nic74.md
.//updates/2019/06/chrome-76-deps-rems.md
.//updates/2018/03/nic65.md
.//updates/2018/10/watch-video-using-picture-in-picture.md
.//updates/2018/07/reportingobserver.md
.//updates/2018/09/inside-browser-part4.md
.//updates/2018/09/reportingapi.md
.//updates/2016/03/access-usb-devices-on-the-web.md

Note:* Introduction to Feature Policy also needs to be updated, but that work will be done while converting to web.dev

What needs to be done?

Feature Policy is being renamed Permission Policy. This has a hard deadline of October 14, if the change makes it into Chrome 87.

• Appropriate type-something label has been added.
• Appropriate section-something label has been added.