Add EnzymeRules for batchnorm

[wsmoses]

Follow up to #536

I made this a separate PR, because for efficiency sake, it is better to have an inplace version of batchnorm, but that wasn't an exported API. Thus I implemented this on the inplace cuda one (which was the only implementation of batchnorm, in place or not).

If NNlib is later refactored to have batchnorm! this can go on the refactored rule.

[mashu]

Few suggestions ;)

1. syntax: more than one semicolon in argument list around around line batchnorm.jl:288
2. refactor into single line all || in if statements as starting new line with || fails compilation on 1.9.3

[CarloLucibello]

There is a weird parsing error in the Code Coverage stage

[CarloLucibello]

Does anyone know about the ubuntu CI error

ERROR: LoadError: Base.Meta.ParseError("parsing error in ext/NNlibCUDACUDNNExt/batchnorm.jl:253: invalid identifier name \"||\"")
Stacktrace:
 [1] amend_coverage_from_src!(fc::FileCoverage)
   @ CoverageTools ~/.julia/packages/CoverageTools/JSYpL/src/CoverageTools.jl:186

?

[mashu]

Does anyone know about the ubuntu CI error

ERROR: LoadError: Base.Meta.ParseError("parsing error in ext/NNlibCUDACUDNNExt/batchnorm.jl:253: invalid identifier name \"||\"")
Stacktrace:
 [1] amend_coverage_from_src!(fc::FileCoverage)
   @ CoverageTools ~/.julia/packages/CoverageTools/JSYpL/src/CoverageTools.jl:186

?

I couldn't compile the branch on my local machine with Julia 1.9.3. I was also running into problems with parser not figuring out it's the new line, see my comment earlier. Basically code won't compile for me without fixing these.

Cheers!