Clean up loader and _findPath functions and elucidate the need for prefix

[AntoineGautier]

The loader function uses a prefix string that is prepended to the list of directories containing Modelica JSON files:

export const MODELICAPATH = [
  `${config.MODELICA_DEPENDENCIES}/template-json/json/`,
];
...
const modelicaDirs = [prefix, ...MODELICAPATH];

Logging the value of prefix when executing npx ts-node scripts/parse-template-package.ts shows that it is either empty or equal to /dependencies/template-json/json/, which is already within MODELICAPATH.
So it seems that prefix can simply be removed.
The variable MODELICAPATH must also be renamed to avoid the confusion with the environment variable: https://github.com/lbl-srg/ctrl-flow-dev/blob/main/server/Dockerfile#L38

The function _findPath has an incorrect JSDoc and its argument reference seems to refer to a full class name. This should be made clearer.

[AntoineGautier]

The confusion between file paths and class names spreads over several functions:

/**
 * Extracts the given file into the type store
 */
export const getFile = (filePath: string) => {
  const jsonData = loader(pathPrefix, filePath);

export class File {
  public package = ""; // only important part of a file
  public elementList: Element[] = [];
  constructor(obj: any, filePath: string) {
    this.package = obj.within;
    const splitFilePath = filePath.split(".");

All these functions expect a full class name (dot notation), not a relative file path.

The only occurrence where the path argument really refers to a file system path is here:
https://github.com/lbl-srg/ctrl-flow-dev/blob/main/server/src/parser/index.ts#L7-L17
But this function is called here:
https://github.com/lbl-srg/ctrl-flow-dev/blob/main/server/scripts/parse-template-package.ts#L12C1-L12C26
with "Buildings" as argument. So, this becomes confusing again because the JSDoc of loadPackage mentions @param packagePath Absolute path to package and "Buildings" is rather a directory that can be found just under the so-called MODELICAPATH in loader.ts.