Add support for binding BLOB values

[gschlager]

Strings with ASCII_8BIT encoding and Extralite::Blob objects will be bound as BLOBs.

db.execute('insert into foo values (?)', File.binread('/path/to/file'))
db.execute('insert into foo values (?)', Extralite::Blob.new('Hello, 世界!'))
db.execute('insert into foo values (?)', 'Hello, 世界!'.force_encoding(Encoding::ASCII_8BIT))

[noteflakes]

Fantastic work @gschlager !

[fractaledmind]

@gschlager: You should come join the Naming Things Discord server. We have a very active group talking about Ruby and SQLite, with a lot of work and discussion in particular about the Extralite gem. We'd love to have you there: https://discord.gg/qKkAanA9