Implement accumulated improvements to Data Explorer backend protocol, add batch profile requests. In Python implement between, search filter types, prototype search_schema RPC, improve filter API

[wesm]

This PR has a batch of improvements to try to catch up with the UI's current state so we can start hooking up filtering for real:

• Modifies filter API and get_column_profiles APIs to group parameters in optional interfaces, e.g. BetweenFilterParams, SetMembershipFilterParams
• Adds search_schema RPC to support column dropdown searching large schemas
• Changes column profile requests to be batch based, so we can request a batch of column null counts all at once
• Renames "set_column_filters" RPC to "set_row_filters" to normalize terminology since we will eventually have "column filters" (e.g. column names starting with "foo") that hide a subset of the columns from view
• Adds summary_stats profile type to provide detailed column summary statistics when needed in the UI
• Adds and implements "between" and "not_between" filter types in Python
• Basic implementation of case-sensitive and case-insensitive text searching (contains/startswith/endswith/regex_match) in Python
• Hooks up basic null percentages into the current summary pane. This code can surely be improved

The focus of the next week will be hooking all this up with the recently-built filtering UI and making sure it works properly.

[wesm]

@jmcphers next week could you have a close look through my changes in data_explorer-backend-openrpc.json? I think the approach I took for different filter types or different profile results is okay for now -- I'm not sure it is so urgent to implement the oneOf union, since this at least makes it clear for each group of properties, which ones must be provided together.

[wesm]

@isabelizimm or @seeM can you have a look at https://github.com/posit-dev/positron/actions/runs/8510379975/job/23307867670?pr=2585? Doesn't seem related to these changes, a build with 1-year old dependencies (that doesn't include IPython, does it?)

EDIT: triaged in main

[jmcphers]

Totally reasonable. So nice to see something other than 29% for the null count! 🎉