Very slow data catalog search

[stevage]

I just searched for "gross domestic" in preview.nationalmap.terria.io and it took over 9 minutes to complete, in Chrome with dev tools open. In that whole time, there was no feedback provided to the user other than the spinning flower thing.

I know we're already aware that search is slow, so this is more of a reminder that it's really slow.

[AnaBelgun]

Implementation using MAGDA as backend

[nf-s]

We now have CatalogIndex which can be used to generate an index of the catalog for fast searching

See

• https://github.com/TerriaJS/terriajs/blob/main/doc/customizing/client-side-config.md#catalogindex
• https://github.com/TerriaJS/terriajs/blob/main/buildprocess/generateCatalogIndex.ts