ui(mongodb): binary, regex and 64-bit values print as Dart objects in the Table and Tree views #1826

Problem

Browsing types_showcase of the compose stack's MongoDB (dev at 25c766c), Table and Tree views print the Dart representation of some BSON values; the JSON (Extended JSON) view is right for all of them.

• Binary: col_binary: BsonBinary(deadbeef) (empty: BsonBinary()), and the type chip in the Tree view says BsonBinary. Expected something like Binary(0xdeadbeef) / BinData(0, "3q2+7w=="), chip bin.
• Regex: col_regex: RegExp: pattern=^querya flags=, type chip _RegExp (a private Dart class name). Expected /^querya/i, chip regex.
• Number colouring in the Tree view: int32 and double are green, but Int64 and Decimal (9223372036854775807, 12345678901234.5678) are plain white.

Where

mongo_documents_table_view.dart / MongoTableGridData (cell text), mongo_document_tree_view.dart (value text, type chip, colours); a shared displayBsonValue(Object?) next to mongo_ejson.dart would give both the same text.

Acceptance

• No BsonBinary(…), RegExp: … or _RegExp in the Table / Tree views; the type chips are the BSON type names.
• All numeric types share one colour in the Tree view.
• A test pins the display text of binary, regex, Int64 and Decimal.