patch 9.1.2146: filetype: cel files are not recognized

patch 9.1.2146: filetype: cel files are not recognized

Problem:  filetype: cel files are not recognized
Solution: Detect *.cel files as cel filetype (Stefan VanBuren).

Reference:
https://cel.dev/
https://github.com/google/cel-java/blob/e36c49febc36bcb16ef4f07274fcc8873c1eee59/testing/src/test/resources/expressions/coverage_test_case/simple_expression.cel
https://github.com/elastic/mito/blob/d0d2dbabae5c563dd943c61fd52992acb655942d/example.cel

closes: #19381

Signed-off-by: Stefan VanBuren <svanburen@buf.build>
Signed-off-by: Christian Brabandt <cb@256bit.org>