Invalid control sequence in translation string "<code>\</code>" of DataExport plugin

Problem/Motivation

I'd like to export a list of all translation strings with `drush locale:export en | msguniq -`.

Steps to reproduce

1. Install the `views_data_export` module in drupal
2. Install the `gettext` package on your system (Debian was used)
3. Export the language strings with `drush locale:export en | msguniq -`.

$ drush locale:export en | msguniq -
<stdin>: warning: Charset missing in header.
                  Message conversion to user's charset will not work.
<stdin>:4632: duplicate message definition...
<stdin>:4: ...this is the location of the first definition
<stdin>:16328:10: invalid control sequence
msguniq: found 2 fatal errors

The translation string at line 16382 is

msgid ""
"Indicates the character used for escaping. Defaults to a backslash "
"([code]\[/code])."
msgstr ""

Proposed resolution

- Use an encoded backlash instead: U+0005C or \

Remaining tasks

User interface changes

API changes

Data model changes