Support partial indexes (`partialFilterExpression`, `sparse`)

[b1ron]

What should be done?

• https://www.mongodb.com/docs/v6.0/core/index-partial/#std-label-index-type-partial
• https://www.mongodb.com/docs/v6.0/core/index-sparse/#sparse-indexes
• https://www.postgresql.org/docs/current/indexes-partial.html

[farcop]

@AlekSi @b1ron Hi guys! Any plans to implement this? We unable to try to switch to FerretDB at least because of this issue.

[AlekSi]

Yes, there should be an updated in a few months.