SCP-3452 chain-index e2e tests (#312)

* SCP-3452: Add chain-index e2e tests

* Compile with TS and added linter

plutus-chain-index/e2e-tests/.eslintignore

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+node_modules
+dist
+.eslintrc.js

plutus-chain-index/e2e-tests/.eslintrc.js

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+module.exports = {
+  root: true,
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    project: "./tsconfig.json",
+  },
+  plugins: [
+    '@typescript-eslint',
+    'sort-imports-es6-autofix',
+  ],
+  extends: [
+    'eslint:recommended',
+    'plugin:@typescript-eslint/recommended',
+  ],
+  settings: {
+    "import/resolver": {
+      "typescript": {}
+    }
+  },
+  rules: {
+    "no-unused-vars": 0,
+    "linebreak-style": [
+      2,
+      "unix"
+    ],
+    "new-cap": 0,
+    "no-unused-expressions": 0,
+    "no-useless-constructor": 0,
+    "sort-imports-es6-autofix/sort-imports-es6": "warn",
+    "sort-imports": ["warn", { ignoreDeclarationSort: true }],
+    "@typescript-eslint/no-floating-promises": ["error"],
+    '@typescript-eslint/explicit-module-boundary-types': 0,
+    "max-len": ["error", { "code": 120 }],
+    "@typescript-eslint/ban-types": 0,
+    '@typescript-eslint/no-non-null-assertion': 0,
+    "@typescript-eslint/no-shadow": ["error"],
+    "@typescript-eslint/no-unused-vars": ['warn', { argsIgnorePattern: '^_', varsIgnorePattern: '^_' }],
+    "@typescript-eslint/no-var-requires": 0,
+    "template-tag-spacing": 0,
+    'promise/avoid-new': 0,
+    'consistent-return': 0, // typescript checks return types
+    "no-shadow": "off", // eslint compains about TS enums hence disable here and enable @typescript-eslint/no-shadow
+    "import/no-unresolved": 0
+  }
+};

plutus-chain-index/e2e-tests/.nvmrc

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+v12.12.0

plutus-chain-index/e2e-tests/README.md

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+# Chain-index end-to-end tests
+
+## Sanity API tests
+
+### Pre-requisites:
+- You have a testnet instance of chain-index running somewhere
+- Chain-index is synced to at least `min_slot` in the environment file `sanity-tests/testnet-env.json`
+- Update URL in environment file if needed
+
+### Run tests:
+- `nvm use` (not required for `nix-shell` users)
+- `npm i`
+- `npm test`
+
+## CI (todo)