- With mock_apollo_client there's no
  reason to use `vm.setData`. This
  actually revealed a bug which is now
  fixed.
- Also improves error message handling.

Part of our prettier migration; changing the arrow-parens style.

Cleaned up the component as well to get rid of redundant props

In order to retrieve single or multiple blobs
from snippets and avoid retrieving all at the
same time, we add a resolver to the blobs field in the
snippet type.

We can now pass a string or an array of files to retrieve.

This is part of the work to implement the consensus reached in the
[RFC][1] to prefer named exports over defalt exports.

Future iterations will migrate existing default exports to named
exports.

The bulk of the changes in this commit were performed with the following
script:

```bash
set -u

changed-files()
{
    local trunk="origin/master"
    local file=
    local committed_files=$(git diff "$trunk"... --numstat \
        | awk '/\.(js|vue)$/{ print $3 }')
    local changed_files=$(git diff --numstat \
        | awk '/\.(js|vue)$/{ print $3 }')
    for file in ${committed_files[@]} ${changed_files[@]}; do
        if [ -f "$file" ]; then
            echo "$file"
        fi
    done
}

git grep -lz "import/prefer-default-export" -- '**/*.js' \
    | xargs -0 perl -0pi -e \
    "s/[^\n]*eslint-disable[^\n]*"\
"import\/prefer-default-export[^\n]*\n//mgs"

git grep -lz "rfcs/-/issues/20" -- '**/*.js' \
    | xargs -0 perl -0pi -e \
    "s/[^\n]*rfcs\/-\/issues\/20[^\n]*\n//mgs"

yarn prettier --write $(changed-files)
```

The script is [idempotent][2], to help make it easier to keep
up-to-date.

[1]: https://gitlab.com/gitlab-org/frontend/rfcs/-/issues/20
[2]: https://en.wikipedia.org/wiki/Idempotence

These no-op default exports have served one or both of these purposes:

1. Preventing `babel-plugin-rewire` from generating an invalid default
   during karma tests;
1. Working around the `import/prefer-default-export` ESLint rule for
   files which only have one named export.

As we recently finished migrating all relevant specs from Karma to Jest,
the first purpose is no longer necessary (with two exceptions, see
below).

The second purpose will become unnecessary once the [RFC][1] to prefer
named exports to default exports is implemented.

As such, this commit removes almost all no-op default exports, and adds
explicit `eslint-disable-next-line` directives (which can be removed
once the RFC is implemented).

---

This work was achieved in a few steps. First, the default exports
explicitly marked as `babel-plugin-rewire` workarounds were removed.

This was achieved via this command:

    rg --color=never -l0 "// prevent babel-plugin-rewire" \
        | xargs -0 \
        perl -0pi -e \
        's/\n+\/\/ prevent babel-plugin-rewire[^\n]*tests'\
    '(?:\nexport default \(\) => {};)?//mgs'

The documentation describing this workaround was then removed by hand.

Unfortunately, two files still participate in Karma tests, and still
need this workaround, so these were reverted manually. Those files (at
the time of writing) are:

    app/assets/javascripts/monitoring/stores/actions.js
    app/assets/javascripts/monitoring/stores/getters.js

Then, all additional no-op default exports were removed with this
command:

    rg --color=never -l0 -F "export default () => {};" \
        | xargs -0 perl -0pi -e 's/\n+export default \(\) => {};//mgs'

Since the `import/prefer-default-export` ESLint rule is still in place,
the files violating it have to disable it explicitly.

With the [RFC][1] to prefer named exports to default exports receiving
wide approval, it makes sense to mark these current violations
_explicitly_ with `eslint-disable-next-line` directives, rather than
_implicitly_ via the no-op default export hack.

The benefit of this approach is that when we disable the
`import/prefer-default-export` rule globally for the RFC, ESLint will
warn about all of these now-unnecessary directives. This will make it
much easier to address all of them (perhaps even automatically, via
`--fix`!).

[1]: https://gitlab.com/gitlab-org/frontend/rfcs/-/issues/20

See https://gitlab.com/gitlab-org/gitlab/-/issues/220785#note_378854721 for more details

In the multi-file scenario for snippets we switch to 'blobs' array
instead of direct 'blob' object

The same GraphQL props/data/query will be used for the Edit
application as well

Default schema for snippet