Add trimmer

src/components/audio-trimmer/audio-trimmer.css

src/components/audio-trimmer/audio-trimmer.jsx

src/components/audio-trimmer/icon--handle.svg

src/components/record-modal/icon--trim.svg

src/components/record-modal/playback-step.jsx

src/components/record-modal/record-modal.css

src/components/record-modal/record-modal.jsx

src/components/waveform/waveform.css

src/components/waveform/waveform.jsx

src/containers/audio-trimmer.jsx

src/containers/playback-step.jsx

src/containers/record-modal.jsx

src/containers/recording-step.jsx

src/lib/audio/audio-buffer-player.js

src/lib/audio/audio-recorder.js