Kebab-case names for `$emit`ted Vue events

The following discussion from !1690 (merged) should be addressed:

• @moffer started a discussion: (+1 comment)

  Eslint complains here to use kebab case.

  oh, it does? then we should include that configuration in client/package.json and make sure it's checked, because there are several more event names in lowerCamelCase through our codebase!

  Could be part of a follow-up though, since that would allow converting all such cases at once. I'll create an issue for it once I learn how to check for the problem!

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Tasks

• adjust the JS Linter to check for this, looks like this?
  https://eslint.vuejs.org/rules/custom-event-name-casing.html
• fix all existing events with lowerCamelCase (one per commit)

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 === (TOPBAR REFACTORING WILL CHANGE THIS) ===
client/src/components/Topbar/Baskets/MenuBasketsEntry.vue:      this.$emit('basketRemove', this.basket.id, userId)
client/src/components/Topbar/Bells/MenuBellsEntry.vue:    @click="$emit('bellRead', bell)"
client/src/components/Topbar/Bells/MenuBellsEntry.vue:    @click.middle="$emit('bellRead', bell)"
client/src/components/Topbar/Bells/MenuBellsEntry.vue:          @click.stop.prevent="$emit('remove', bell.id)"
client/src/components/Topbar/Messages/MenuMessagesEntry.vue:      this.$emit('chatOpened')

src/Modules/Dashboard/components/ActivityOptionListings.vue:      this.$emit('reloadData')

src/Modules/Region/components/ThreadPost.vue:              @reactionAdd="$emit('reactionAdd', $event)"
src/Modules/Region/components/ThreadPost.vue:              @reactionRemove="$emit('reactionRemove', $event)"

src/Modules/Region/components/ThreadPostActions.vue:          this.$emit('reactionRemove', key)
src/Modules/Region/components/ThreadPostActions.vue:        this.$emit('reactionAdd', key)

src/Modules/Register/components/RegisterLegalAgreement.vue:      @change="$emit('update:acceptGdpr', $event)"
src/Modules/Register/components/RegisterLegalAgreement.vue:      @input="$emit('update:acceptLegal', $event)"
src/Modules/Register/components/RegisterLegalAgreement.vue:      @input="$emit('update:subscribeNewsletter', $event)"

src/Modules/Register/components/RegisterSuccess.vue:        @click="$emit('loadLogin')"

src/Modules/Voting/components/MultiSelectionVotingComponent.vue:    votingRequestValues () { this.$emit('updateVotingRequestValues', this.votingRequestValues) }
src/Modules/Voting/components/MultiSelectionVotingComponent.vue:    this.$emit('updateValidSelection', true)
src/Modules/Voting/components/MultiSelectionVotingComponent.vue:    this.$emit('updateVotingRequestValues', this.votingRequestValues)
src/Modules/Voting/components/ScoreVotingComponent.vue:    votingRequestValues () { this.$emit('updateVotingRequestValues', this.votingRequestValues) }
src/Modules/Voting/components/ScoreVotingComponent.vue:    this.$emit('updateValidSelection', true)
src/Modules/Voting/components/ScoreVotingComponent.vue:    this.$emit('updateVotingRequestValues', this.votingRequestValues)
src/Modules/Voting/components/SingleSelectionVotingComponent.vue:    isValidSelection () { this.$emit('updateValidSelection', this.isValidSelection) },
src/Modules/Voting/components/SingleSelectionVotingComponent.vue:    votingRequestValues () { this.$emit('updateVotingRequestValues', this.votingRequestValues) }
src/Modules/Voting/components/SingleSelectionVotingComponent.vue:    this.$emit('updateValidSelection', this.isValidSelection)
src/Modules/Voting/components/SingleSelectionVotingComponent.vue:    this.$emit('updateVotingRequestValues', this.votingRequestValues)
src/Modules/Voting/components/ThumbVotingComponent.vue:    votingRequestValues () { this.$emit('updateVotingRequestValues', this.votingRequestValues) }
src/Modules/Voting/components/ThumbVotingComponent.vue:    this.$emit('updateValidSelection', true)
src/Modules/Voting/components/ThumbVotingComponent.vue:    this.$emit('updateVotingRequestValues', this.votingRequestValues)
src/Modules/Voting/components/VoteForm.vue:        this.$emit('disableVoteForm')

 === (STOREWALL REFACTORING WILL CHANGE THIS) ===
src/Modules/WallPost/components/WallPost.vue:      @ok="$emit('deletePost', post.id)"