Restructure project directories (#333)

`/client/web` -> `/frontend`
`/client/cli` -> *delete for now*
`/client/native` -> *delete for now*
`/core/editor` -> `/editor`
`/core/document` -> `/graphene`
`/core/renderer` -> `/charcoal`
`/core/proc-macro` -> `/proc-macros` *(now plural)*

frontend/src/components/widgets/buttons/IconButton.vue

@@ -0,0 +1,67 @@
+<template>
+	<button class="icon-button" :class="`size-${String(size)}`" @click="action">
+		<IconLabel :icon="icon" />
+	</button>
+</template>
+
+<style lang="scss">
+.icon-button {
+	display: inline-flex;
+	justify-content: center;
+	align-items: center;
+	flex: 0 0 auto;
+	padding: 0;
+	outline: none;
+	border: none;
+	border-radius: 2px;
+	background: none;
+	vertical-align: top;
+	fill: var(--color-e-nearwhite);
+
+	// The `where` pseduo-class does not contribtue to specificity
+	& + :where(.icon-button) {
+		margin-left: 0;
+	}
+
+	&:hover {
+		background: var(--color-6-lowergray);
+		color: var(--color-f-white);
+		fill: var(--color-f-white);
+	}
+
+	&.size-12 {
+		width: 12px;
+		height: 12px;
+	}
+
+	&.size-16 {
+		width: 16px;
+		height: 16px;
+	}
+
+	&.size-24 {
+		width: 24px;
+		height: 24px;
+	}
+
+	&.size-32 {
+		width: 32px;
+		height: 32px;
+	}
+}
+</style>
+
+<script lang="ts">
+import { defineComponent } from "vue";
+import IconLabel from "@/components/widgets/labels/IconLabel.vue";
+
+export default defineComponent({
+	props: {
+		action: { type: Function, required: true },
+		icon: { type: String, required: true },
+		size: { type: Number, required: true },
+		gapAfter: { type: Boolean, default: false },
+	},
+	components: { IconLabel },
+});
+</script>