fix: Move content into to frontend directory

Doing this BEFORE the merge prevents a lot of merge conflicts.

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

frontend/src/components/common/copyable/copyable-field/copyable-field.tsx

@@ -0,0 +1,67 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import React, { useCallback, useMemo } from 'react'
+import { Button, FormControl, InputGroup } from 'react-bootstrap'
+import { useTranslation } from 'react-i18next'
+import { ForkAwesomeIcon } from '../../fork-awesome/fork-awesome-icon'
+import { ShowIf } from '../../show-if/show-if'
+import { Logger } from '../../../../utils/logger'
+import { isClientSideRendering } from '../../../../utils/is-client-side-rendering'
+import { CopyToClipboardButton } from '../copy-to-clipboard-button/copy-to-clipboard-button'
+
+export interface CopyableFieldProps {
+  content: string
+  shareOriginUrl?: string
+}
+
+const log = new Logger('CopyableField')
+
+/**
+ * Provides an input field with an attached copy button and a share button (if supported by the browser).
+ *
+ * @param content The content to present
+ * @param shareOriginUrl The URL of the page to which the shared content should be linked. If this value is omitted then the share button won't be shown.
+ */
+export const CopyableField: React.FC<CopyableFieldProps> = ({ content, shareOriginUrl }) => {
+  useTranslation()
+
+  const sharingSupported = useMemo(
+    () => shareOriginUrl !== undefined && isClientSideRendering() && typeof navigator.share === 'function',
+    [shareOriginUrl]
+  )
+
+  const doShareAction = useCallback(() => {
+    if (!sharingSupported) {
+      log.error('Native sharing not available')
+      return
+    }
+    navigator
+      .share({
+        text: content,
+        url: shareOriginUrl
+      })
+      .catch((error: Error) => {
+        log.error('Native sharing failed', error)
+      })
+  }, [content, shareOriginUrl, sharingSupported])
+
+  return (
+    <InputGroup className='my-3'>
+      <FormControl readOnly={true} className={'text-center'} value={content} />
+      <InputGroup.Text>
+        <CopyToClipboardButton variant={'outline-secondary'} content={content} />
+      </InputGroup.Text>
+      <ShowIf condition={sharingSupported}>
+        <InputGroup.Text>
+          <Button variant='secondary' title={'Share'} onClick={doShareAction}>
+            <ForkAwesomeIcon icon='share-alt' />
+          </Button>
+        </InputGroup.Text>
+      </ShowIf>
+    </InputGroup>
+  )
+}