Text Searching to determine Rank of File

What

In short, this program:

Consumes the contents of each file within a specified directory
Represents that file as a Trie in Memory
Enables searching of the generated Trie and determines the rank of each file (0 -> 100) where 100 = contains the full search term

Running with sbt:

sbt version in this project: 1.6.2
sbt script version: 1.6.2

It runs against scala 2.12

Jetbrains project init seems to have set build.sbt as scalaVersion 3.1.2 (I have no idea hey).

To start up the program

> sbt
> runMain Main /Path/To/Required/Directory/

Once within the program, simply enter the words to search

> search: <your words here>
> {fileName}: X%
> {fileName}: Y%

In order to quit, simply type :quit into the search field

> search: :quit

The iterate call is manually tested, with no code-based regression
The logic to consume a file's contents into a List of words could be done in closer to O(n) time using a more complex reduce call. This was opted against in favour of readability.
A choice was made to make the Trie representation generic. It could be set as Char but part of the design here is extensibility.