Add support for `or` in line filters

[kelnage]

Loki has added support for an or operator to combine equality line filters, which would remove the need to convert them into regular expressions. I.e., previously to require a line contains either A or B you had to use:

|~ `A|B`

This meant we needed to escape the values A and B (in case they contained regular expression meta-characters). Now we can instead use:

|= `A` or `B`