The CiEnvironment.json file contains an array of CiEnvironment structs for
all the supported CI servers. Each property of a CiEnvironment struct
is an expression that evaluates a value from one or more environment variables.
The expression syntax for environment variables can use the form ${variable/pattern/replacement},
similar to bash parameter substitution,
but inspired from sed's s command
which provides support for capture group back-references in the replacement.