build: add husky ignored files to .gitignore (#20856)
build: add husky ignored files to .gitignore (#20856)

Ahead of upgrading to husky v5, adding the shell file location
to .gitignore to prevent it from randomly showing up when devs
checkout older branches.
andrewseguin/material2,josephperrott/material2,angular/components,josephperrott/material2,crisbeto/material2,andrewseguin/material2,andrewseguin/material2,mmalerba/material2,andrewseguin/material2,mmalerba/material2,angular/components,DevVersion/material2,mmalerba/material2,crisbeto/material2,josephperrott/material2,crisbeto/material2,angular/components,DevVersion/material2,andrewseguin/material2,DevVersion/material2,josephperrott/material2,DevVersion/material2,DevVersion/material2,angular/components,mmalerba/material2,josephperrott/material2,mmalerba/material2,crisbeto/material2