feat: extend literal conversion support

[vbarua]

Adds Calcite conversion support for VarCharLiteral and FixedBinaryLiteral.

Additionally, forces

• StrLiteral to be converted to VARCHAR
• BinaryLiteral to be converted to VARBINARY

Before this, they were converted to

• CHAR()
• BINARY()

respectively. If those types are desired, Substrait has the FixedChar and FixedBinary types.

Calcite being a bit to smart when converting these two types results in failures during query planning.