chore: 著作権とライセンスについての情報を各ファイルに追加する (#11348)

* chore: Add the SPDX information to each file

Add copyright and licensing information as defined in version 3.0 of
the REUSE Specification.

* tweak format

---------

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/frontend/src/components/global/MkCustomEmoji.vue

@@ -1,3 +1,8 @@
+<!--
+SPDX-FileCopyrightText: syuilo and other misskey contributors
+SPDX-License-Identifier: AGPL-3.0-only
+-->
+
 <template>
 <span v-if="errored">:{{ customEmojiName }}:</span>
 <img v-else :class="[$style.root, { [$style.normal]: normal, [$style.noStyle]: noStyle }]" :src="url" :alt="alt" :title="alt" decoding="async" @error="errored = true" @load="errored = false"/>