Nickel rules for Bazel

These are build rules for generating configuration files using Nickel during a Bazel build.

Build Rules

nickel_export(name, src, deps=[], format="json", out)

Evaluate a Nickel file and export the result.

Attribute	Description
`name`	Unique name for this rule (required)
`src`	Nickel file to evaluate (required)
`deps`	List of other Nickel files required for evaluation
`format`	Export format, must be one of `"json", "yaml", "toml", "raw"`
`out`	Output file name (required)