Fix technical debt cause by Merge Request Notes refactor

While debugging the code added here https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#3ce7f1dd43287a1d04e957283a8f7ff4e3f60ec3_80_93

I found the following problems:

  1. camelCaseKeys function is duplicated and is not used. This was pointed in the MR, but somehow was merged. Fixed in: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17667

  2. Sprintf with user generated content needs to be escaped: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#e75a068a217e33deac9009c31c835d7b972d2210_67_79

  3. Do i18n properly:https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62474836

  4. v-html shouldn't be used:

  5. https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#d63222f7e9a4ec7b560a9e43597e4de7c2e4fffc_0_32

  6. https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62474886

  7. Identation doesn't follow the styleguide: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#3e9f352f8d1d561f5108008cbec308921f6eb9d5_0_82

  8. SVGs should use icon.vue: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#a8841151b538089b177018118015a54d494223a3_0_45

  9. A span with type=button https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#a8841151b538089b177018118015a54d494223a3_0_77

  10. a class named .line-resolved-text: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#a8841151b538089b177018118015a54d494223a3_0_77

  11. button without type: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62474218

  12. Unecessay reassignment https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62474165

  13. Button without type https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#d7023f611ef2e7cf7310e5813e81acb8bf38ed6f_171_184

  14. loading_icon.vue should have been used https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62476132

  15. icon.vue should have been used: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62476218

  16. no button type https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62476243

  17. Unresolved fixme comment: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62476357

  18. foreach was used instead of reduce. Decreases performance & readability: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62473611

  19. Improve variable naming: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62476577

  20. what is this foreach doing? https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#note_62473672

  21. component order is not the same as the styleguide: https://gitlab.com/gitlab-org/gitlab-ce/commit/059ab73b8eae3a546d0a19fe99ef0c52df5fac01#5ff60f23cdeb24af173d741ad2c3373aa3b23d35_0_1