feat(bqls): Add bqls support

[joshbode]

Adds support for BigQuery language server.

thanks @kitagry

[glepnir]

Thanks. But we have some rules for new servers. Please see https://github.com/neovim/nvim-lspconfig/blob/master/CONTRIBUTING.md#adding-a-server-to-lspconfig

could you provide some more information about this server how popular it is

[joshbode]

I would say not very popular (yet!) but maybe @kitagry has some more context (there is a plugin that adds the config dynamically).

I was hoping that adding support would increase the exposure of this LS, which appears to provide better support for BigQuery than the existing sqlls server.

[glepnir]

It's a great server. But it's only 7 stars at the moment. And it doesn't have the same download volume as other editors like vscode. So I think we can wait a little longer to avoid our repo becoming bloated with some small and unpopular server configuration.