data explorer: create an "is filtering" context key

[isabelizimm]

similar to the "is sorting" context key in the data explorer, we want to be able to tell if the user has applied any sorts. then, we'll want to have the "Convert to Code" button only be active if there is filtering or sorting.

[rodrigosf672]

Verified Fixed

Positron Version(s) : 2025.10.0 (Universal) build 8
OS Version          : macOS Sequoia 15.6

Test scenario(s)

• Applied to sorting can be correctly converted to code (both in terms of order of sorting as well as ascending/descending state). See example below.
• Applied to sorting+filtering can be both converted to code.

Identified two issues to be discussed and potentially logged. I'll check with @isabelizimm after the holiday first, but the issues are tiny and perhaps even known. This is not something to hold the release for.

• Keybinding can be used to bypass not applicable data frames to code scenarios. If user opens the Convert to Code pop-up through a keybinding to a not applicable data frame, this is what they may get. Notice that, in these scenarios, Convert to Code button is rightfully disabled or not present at all, but the keybinding can bypass that.

- Let there be columns A and B. When A is sorted, B’s sort should be restricted to act only within A’s groups, preserving the overall A order. There may be some scenarios that the code cannot fully encompass the sorting logic. Not sure if this has already been discussed, but I'd like to take some more time double-checking such scenarios.

cc @testlabauto