WebP compatibility encoder

The bundled webp_codec.wasm is the exact binary shipped by Microsoft Playwright
1.62.1, compiled from Google libwebp with Emscripten. Original licenses and patent
notices are retained in webp_codec.LICENSE alongside this file.

Source: https://github.com/microsoft/playwright/tree/v1.62.1/packages/utils/webp
libwebp: https://github.com/webmproject/libwebp

The small browser worker/loader in this project is our own ABI adapter. No
Playwright automation runtime or npm dependency tree is shipped to visitors.