Ability to customize interpolation prefix/suffix

[zleight1]

Is your feature request related to a problem? Please describe.

We use i18next (vue-i18next + react, etc.) and the default interpolation uses double braces {{ param }}.

While we can set the interpolation on i18next to use singles braces like vee-validate, this leads to confusion as any documentation or examples online are going to use double braces.

Also, theoretically we could only use single braces for texts that feed into vee-validate, but again this is mixing and inevitably leads to issues down the road. We also have a mix of React and Vue so there would be inconsistency amongst projects (micro-frontends).

Describe the solution you'd like

The ability to customize the interpolation, at minimum to allow double braces but ideally for flexibility it could take any pattern to align with other standards.

Describe alternatives you've considered

Described in the feature request, but generally setting the other libraries to single braces or mixing.

[zleight1]

I'm going to attempt to implement this myself, it looks like this would just be an option to the constructor and then it'd be passed down through all calls to interpolate.