Lint `.json` files (#6852)

We've been using the `eslint-plugin-json` plugin for some time, but we
haven't been visiting `.json` files in the lint script. The lint script
has now been updated to incude `.json` files, which means any invalid
JSON will result in a lint error.

Unfortunately this JSON plugin doesn't seem to apply the other eslint
rules (such as `key-spacing`) to the JSON files. I wasn't able to find a
way to get that to work. Instead I manually auto-formatted each of the
locale `message.json` files, which fixed many whitespace
inconsistencies.

The `states.json` file was deleted completely, as it appears to be
unused. It wasn't a valid JSON file anyway, it was JavaScript. It looks
like a `states.js` file is automatically generated, but an old copy was
accidentally saved as `states.json` and included in the repo.

Many duplicate key errors were found and fixed in the
`development/states/` JSON files.

`package-lock.json` was added to `.eslintignore` because it was very
slow to lint, and linting it doesn't provide much value.

1 files changed, 2 insertions, 2 deletions

diff --git a/app/_locales/sl/messages.json b/app/_locales/sl/messages.json
index d04ba1ee7..563bae1b1 100644
--- a/app/_locales/sl/messages.json
+++ b/app/_locales/sl/messages.json
@@ -1145,7 +1145,7 @@
   },
   "seedPhraseAlert": {
     "message": "Opozorilo o seed phrase"
-  },  
+  },
   "select": {
     "message": "Izberi"
   },
@@ -1549,6 +1549,6 @@
     "message": "Vaš zasebni seed phrase"
   },
   "zeroGasPriceOnSpeedUpError": {
-    "message":"Ničelni gas price na pospešitvi"
+    "message": "Ničelni gas price na pospešitvi"
   }
 }