Initial import of percent-encoding v2.1.0 am: 86d7986f55 am: c299b75b3e

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/percent-encoding/+/1533063

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I4389cdecea1410a42aabdea898778db20a0fce74