case when expressions that aren't boolean data type cause panic

[Jefffrey]

Describe the bug

Given case expression in following form:

CASE
  WHEN x1 THEN y1
  WHEN x2 THEN y2
  ELSE y3
END

Then all xN (x1, x2) should be boolean expressions and should be coerced to a boolean type if not, otherwise throw an error without causing a panic.

To Reproduce

On latest main:

jeffrey:~/Code/arrow-datafusion/datafusion-cli$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.30s
     Running `/media/jeffrey/1tb_860evo_ssd/.cargo_target_cache/debug/datafusion-cli`
DataFusion CLI v21.0.0
❯ select CASE WHEN 1 THEN null ELSE 10 END as col;
thread 'main' panicked at 'WHEN expression did not return a BooleanArray: Internal("could not cast value to arrow_array::array::boolean_array::BooleanArray")', /home/jeffrey/Code/arrow-datafusion/datafusion/physical-expr/src/expressions/case.rs:199:18
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
jeffrey:~/Code/arrow-datafusion/datafusion-cli$

Expected behavior

Should either succeed, or throw error without panic

Additional context

Will be fixed in #5820