feat: avoid displaying the key until loading

[rozsazoltan]

If the page is not loaded based on SSR, then when the language file loading takes even slightly longer than the rest of the frontend, the key briefly appears for a very short time. This creates a sensation of "vibration". It would be much better if the wTrans (and other dependent functions) function returned nothing until the loading is complete.

I've made a video (not the most professional, but it illustrates the difference), playing back the loading process at 0.1x speed.

laravel-vue-i18n-loading-text-slowdown.mp4

[rozsazoltan]

Hm, GitHub won't let me place the PR in Draft. The implementation is still half-done / incomplete.

Maybe we should complement it with another global setting, which by default allows displaying the key.

showKeyWhileLoading = true // (default)

And for a false value, it would return an empty string.

Althought displaying the key would only be advantageous in the main (99% English) language, and only in cases where the key covers entire words/sentences that are meaningful on their own, rather than just a structure like section.example.key.to.text.

[xiCO2k]

this is a breaking change :(

I could consider that if we make that an option like: hiddenBeforeLoaded, that way we can have this on a Minor Release.

Thanks for the PR.