Handle empty cookies in JA4H Zeek parsing

[Squiblydoo]

This PR fixes a bug mentioned here: #123

After the sorting of the cookies and before building the JA4H string, it checks to see if the JA4H_c_r and JA4H_d_r values are empty, if so, it assigns the JA4H_c or _d values with twelve 0s; if they are not empty, it will hash them as normal.

I confirmed that this works as expected, see parsing of Zeek logs below:

The PR looks like I changed a lot more than this, but the other thing I changed was the indentation.
Some parts of this script contain 2 spaces for the first level indent, followed by a 4 spaces for the second level indent. This felt inconsistent and made it more difficult to modify the code than it should have.
Other parts of the code use 4 spaces for the first level indent, so I modified this section to fit that pattern. (I did not modify all places where two spaces were used, as it seemed out of scope.)

I confirmed that the use of 4 spaces for the first level indent did not impact functionality, and the script appears to be working as expected.

[Squiblydoo]

Oh , I just noticed that someone else suggested a similar fix 2 days ago: #157

[john-althouse]

Thanks @Squiblydoo! I like your implementation better because it assigns the value of "000000000000" to ja4h_c and ja4h_d - which is better for if someone were to build extra Zeek scripts and call these values.