Generate index with kebab casing generates invalid index file

[scurker]

🐛 Bug Report

Running @svgr/cli against a directory with out-dir and --filename-case kebab generates an invalid index file.

To Reproduce

Steps to reproduce the behavior:

Assuming a directory structure similar to this:

└─ icons
   ├─ foo.svg
   ├─ bar.svg
   └─ foo-bar.svg

svgr icons --out-dir icons --filename-case kebab would generate the following index template:

export { default as foo } from './foo'
export { default as bar } from './bar'
export { default as foo-bar } from './foo-bar'

Expected behavior

foo-bar is not a valid export and will break subsequent imports. I'm not sure what the desired output should be, but perhaps the default export should be Pascal cased for the index file while the filenames remain kebab cased.

Run npx envinfo --system --binaries --npmPackages @svgr/core,@svgr/cli,@svgr/webpack,@svgr/rollup --markdown --clipboard

Paste the results here:

## System:
 - OS: macOS Mojave 10.14.6
 - CPU: (12) x64 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
 - Memory: 107.21 MB / 16.00 GB
 - Shell: 3.2.57 - /bin/bash
## Binaries:
 - Node: 10.15.3 - /usr/local/bin/node
 - Yarn: 1.21.1 - /usr/local/bin/yarn
 - npm: 6.4.1 - /usr/local/bin/npm

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[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.