Fixes#1258
Add user permissions for uploading podcasts and downloading episodes.
* Update `client/components/app/SideRail.vue` to check for `userCanUpload` instead of `userIsAdminOrUp` for podcast search and download queue links.
* Add `getUserCanUpload` getter in `client/store/user.js` to check the new `upload` permission.
* Update `server/controllers/PodcastController.js` to allow users with the `upload` permission to create and download podcasts.
* Add `upload` permission for non-admin users in `server/models/User.js`.
* Add `upload` permission toggle switch in `client/components/modals/AccountModal.vue`.
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