Add mixed-case support for BlackHole connector

[Mariamalmesfer]

Description

Enables mixed-case identifier support in the BlackHole connector.

Motivation and Context

Before:
BlackHole treated MyTable, mytable, and MYTABLE as the same table.

Now:
You can enable a config to keep the original casing, so those names are treated as different tables. By default, it stays case-insensitive.

Impact

Test Plan

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Release Notes

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== RELEASE NOTES ==

BlackHole Connector Changes
* Added support for case-sensitive identifiers in BlackHole. Enable by setting case-sensitive-name-matching=true in the catalog config.

[steveburnett]

Suggest adding Configuration Properties table to the BlackHole connector doc. You can use the table in the MySQL connector doc as a model which has case-sensitive-name-matching in the last row.