fix(vue): support optional chaining

[dhayab]

This PR updates dependencies for Vue InstantSearch templates, to add support for optional chaining.

[Haroenv]

What do you plan to use it for? is it maybe possible to regenerate with a more modern config that supports this + others out of the box? maybe via vite?

[dhayab]

@Haroenv this was a quick win I found when adapting the Autocomplete x Vue InstantSearch guide for Vue 2. I'll set aside an hour or two to replace those with a vite-based boilerplate. Also, I had doubts about updating the Vue InstantSearch 2 template but maybe it is not necessary, since the last release (2.7.1) was ~2y ago. Wdyt?

[sarahdayan]

+1 for using this as an opportunity to go with a more modern toolchain—if this doesn't take too long and doesn't create time consuming issues to solve.

[dhayab]

@Haroenv @sarahdayan I looked into it and I'm not positive we should move the template to Vite.

Vue 2 support in Vite depends on a community plugin (https://github.com/underfin/vite-plugin-vue2), and although it seems maintained by a known figure in the Vue community, it might create unforeseen issues / support requests, compared to bumping @vue/cli and its dependencies. Wdyt?

[Haroenv]

Yes, that indeed doesn't sound better. Maybe then babel preset env just needs to be updated? It just seems a little odd to add only the optional chaining explicitly, as it's no longer a proposal

[Haroenv]

lgtm when CI passes :)