Lucee code style guide

Based on the comments on this PR:

Apparently at some point in the future a formatter will be run against the
codebase. It also suggests that no formal style guide is already available
for the Lucee codebase. If that is the case, one must either be drafted,
or copied from some other well-known, established Java project. Preferably
this would be provided in human-readable form, as well as a format that can
be easily imported into an IDE or some other code formatting tool.