Pushdown all dot notation queries for Tigris

[AlekSi]

Blocked by tigrisdata-archive/tigris#838.

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What should be done?

Let's implement dot notation pushdowns for everything we currently support for PostgreSQL.

• Filtering document fields via foo.bar
• Filtering array items via foo.0
• Filtering fields of nested documents inside arrays via foo.0.bar
• Filtering foo.0.bar.1.baz

Only arrays support should be missing, but let's check.

[AlekSi]

If we manage to query nested documents inside arrays without specyfing index foo.bar for PostgreSQL, it's also in the scope of this issue (if it's possible to implement). {foo: {bar: 1}} or {foo: [{bar: 1}]} can be possible.

I don't think that {"foo": {"bar": 1}} and {"foo.bar": 1} are equivalents: the former matches the whole document, while the latter checks only one field. See https://www.mongodb.com/docs/manual/tutorial/query-embedded-documents/