feat: Add support for paste event

[robertfausk]

Please check if the PR fulfills these requirements

• It's the right issue type on the title
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number) no issue exists yet - so it is not needed
• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes/features)
• Docs have been added/updated (for bug fixes/features)
• It does not introduce a breaking change or has a description of the breaking change

Description

Add support for paste event to be able to hook into image adding or something else.

Example:

        <editor
            :options="tuiEditorOptions"
            @paste="onEditorPaste"
            ref="tuiEditor"
            ...
        />

...
        data () {
            return {
                ...
                tuiEditorOptions: {
                    ...
                    hooks: {
                        addImageBlobHook: function (blob, callback) {
                            window.vueApp.uploadImage(blob).then(function (uploadedImageURL) {
                                callback(uploadedImageURL);
                            });
                        }
                    },
                },
            }
        },
        methods: {
            onEditorPaste (event) {
                var cbData = event.data.clipboardData;
                var types = cbData && cbData.types;

                if (types.includes("Files")) {
                    const blob = cbData.files['0'];
                    this.$refs.tuiEditor.editor.eventManager.emit('addImageBlobHook', blob, (imageUrl, altText) => {
                          this.$refs.tuiEditor.editor.eventManager.emit('command', 'AddImage', {
                            imageUrl,
                            altText: altText || blob.name || 'image'
                        });
                    }, 'paste');

                    event.data.preventDefault();
                    event.data.stopPropagation();
                }
            },
            uploadImage(blob) {
                let formData = new FormData();
                let path = this.getHiddenTuiEditorInput().dataset.uploadImagePath;

                // file in a 'multipart/form-data' request
                formData.append(0, blob, blob.name);

                return fetch(path, {
                    method: 'POST',
                    body: formData
                }).then(response => {
                    if (!response.ok) {
                        throw new Error('Server or network error');
                    }

                    return response.json();
                }).then(function(myJson) {
                    return myJson.imagePath
                });
            }
        }
...

---

Thank you for your contribution to TOAST UI product. 🎉 😘 ✨

[robertfausk]

@sohee-lee7 @dongsik-yoo
Are there any updates on this?
I would like to get it merged and tagged so that I do not need to use my own fork anymore.

[dongsik-yoo]

@sohee-lee7 @seonim-ryu Check this PR.