Wrong calculation for initial file size

Nobody has claimed this yet.

# Bug

## Expected Behavior

Given a gzipped file in url
When loading the page
Then the calculated file size is correct.

Given a cc.json file in url
When loading the page
Then the calculated file size is correct.

## Actual Behavior
The calculated file size is always 13 for gzipped files and 15 for not gzipped files.

## Steps to Reproduce the Problem
1. copy app/codeCharta/assets to *dist/webpack* which is the static file server in dev mode
2. run in dev mode (`npm run dev`)
3. add a debugger to the calculation
4. open in browser e.g. http://localhost:3000/?file=assets%2Fsample3.cc.json, http://localhost:3000/?file=assets%2Fsample2.cc.json&file=assets%2Fsample3.cc.json or http://localhost:3000?file=assets%2Foutput.cc.json.gz

## Technical analysis
Calculated file size for gzipped files comes from `response.body.toString().length` . `response.body` is a blob in that case. Therefore `response.body.toString()` is always the string `"[object Blob]"` and its length is `13`

Calculated file size for not gzipped files comes from `response.body.toString().length` . `response.body` is an object in that case. Therefore `response.body.toString()` is always the string `"[object Object]"` and its length is `15`

Note that previous *urlExtractor.spec.ts* mocked the http get request falsely as below. Therefore some tests had a different file size. But in reality initially it receives always a blob or an object. Also note that this complete parsing gets only called for initial map loading. Manual uploading a map doesn't utilize the `urlExtractor`.
```ts
$http.get = jest.fn().mockImplementation(async () => {
return { data: '{"checksum": "fake-md5", "data": {"apiVersion": 1.3, "nodes": []}}', status: 200 }
})
```

## Open question
Do we need the calculation, when it currently is a "random small hardcoded number" and no one has noticed?

What is actually the correct calculation? Should it be the length of (unzipped) text content of file? It seems to be used for map size resolution somehow? (see `getMapResolutionScaleFactor` within *codeMapHelper.ts*.

## Specifications
- is released in [online-demo](https://maibornwolff.github.io/codecharta/visualization/app/index.html?file=codecharta.cc.json.gz&file=codecharta_analysis.cc.json.gz): yes
- CodeCharta Version: 1.109.1

Start with the initial loading path in urlExtractor.ts and its urlExtractor.spec.ts tests, then inspect getMapResolutionScaleFactor in codeMapHelper.ts. Reproduce the issue with npm run dev and the example URLs, and determine the intended file-size calculation. Done means the calculation reflects the actual response types and the tests cover gzipped and non-gzipped files.

Written by the indexing model from the issue text.