.Net: [MEVD] Implement support for score threshold

[roji]

For providers which don't natively support score threshold, I've gone with applying the filter client-side - the other option would be to throw.

• In EF we're quite strict on not bringing back database data in order to client-evaluate; in other words, if the user wants to load database rows from the database and then perform some post-filtering, they need to write that explicitly in code, to avoid scenarios where tons of data gets unintentionally transferred.
• In MEVD we already implement Skip in various providers by bringing back the entire matching resultset and then filtering client-side. This is potentially much worse than filtering for score threshold client-side, as the amount of extra data brought back by threshold post-filtering is limited to top (k), whereas with Skip/pagination queries that amount of data grows with each page.
• Ultimately, MEVD is simpler and more high-level, and is also explicitly designed for layers to be composed on top (e.g. MEDI). So there does seem to be more value in features "just working" across providers.

Closes #9566

[moonbox3]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
core_plugins/sessions_python_tool
sessions_python_plugin.py	178	12	93%	100, 124, 126–127, 129, 131, 133, 141, 215–216, 250–251
TOTAL	28130	4825	82%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3812	23 💤	0 ❌	0 🔥	1m 45s ⏱️