Repository: vscode
Issue: Proxy parameters are ignored and user-settings are missing a proxy-bypass option
Labels: bug,proxy

### Issue Type
Bug

### Description

@joaomoreno mentioning you here as discussed in https://github.com/Microsoft/vscode-docs/pull/1069

**Steps to reproduce**

1. Start VSC using `code --proxy-server="myproxy:8080" --proxy-bypass-list="*.someinternaldomain" --ignore-certificate-errors`
2. Make sure in the user settings the options `http.proxy` and `http.proxyStrictSSL` are  **not** set. 

**Expected outcome:** 
VSC should use the proxy myproxy:8080 for ALL protocols except when connecting so any subdomain on *.someinternaldomain*. Also it should ignore any SSL errors. This should be true for all VSC parts that require networking and all plug-ins that do so.

**Actual outcome:**
All submitted cmd parameters seem to be ignored atleast for parts of VSC.

**Observed behaviour:**
Create a JSON-Schema that is referencing both a public URL and an internal URL, e.g.

```JSON
{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "type": "object",
    "properties": {
        "something": {
            "$ref": "https://repo.someinternaldomain/some-internal-schema.json"
        }
    }
}
```

where some-internal-schema.json can be an blank JSON such as 
```JSON
{}
```				

VSCode will then try to resolve both: the internal and the public domains. Given the cmd params we used to start VSC both should work. But actually what I get is 
				

```LOG
Unable to load schema from 'repo.someinternaldomain'. Error: self signed certificate in certificate chain
```

Testing further, I set the option `"http.proxyStrictSSL" : false` in the VSC user settings, the certificate error now is replaced by the following error:

```LOG
Unable to load schema from 'http://json-schema.org/draft-07/schema': Unable to connect to http://json-schema.org/draft-07/schema. Error: connect ECONNREFUSED 127.0.0.1:80
```

Note that on the same system I am able to visit json-schema.org without any issues using the same proxy configuration. This can be also tested when setting `"http.proxy": "http://myproxy:8080"` in the user settings. Then the error will go away. 
Now public connections are working just fine but the internal connections will still not work because `--proxy-bypass-list`, just like all the other cmd parameters seems to be ignored.

So the issue is: 
1. chromium proxy parameters as shown above are ignored by some parts of VSC (used for JSON schema validation). Note that this also happens with `code --disable-extensions` so I believe this is a built-in feature.
2. a option to configure a proxy-bypass-list in the user-settings is missing (this would be a great addition not only because the parameters are not working but in general)

### VS Code Info

VS Code version: Code 1.20.1 (f88bbf9137d24d36d968ea6b2911786bfe103002, 2018-02-13T15:34:36.336Z)
OS version: Windows_NT x64 6.3.9600

<details>
<summary>System Info</summary>

|Item|Value|
|---|---|
|CPUs|Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz (2 x 2497)|
|Memory (System)|8.00GB (6.40GB free)|
|Process Argv|C:\Program Files\Microsoft VS Code\Code.exe|
|Screen Reader|no|
|VM|100%|

</details><details><summary>Extensions (18)</summary>

Extension|Author (truncated)|Version
---|---|---
rainbow-brackets|2gu|0.0.6
npm-intellisense|chr|1.3.0
vscode-markdownlint|Dav|0.13.0
vscode-eslint|dba|1.4.7
githistory|don|0.4.0
vscode-generate-getter-setter|DSK|0.4.2
gitlens|eam|8.0.2
EditorConfig|Edi|0.12.1
tslint|eg2|1.0.28
LogFileHighlighter|emi|2.1.1
json-tools|eri|1.0.2
docthis|joe|0.6.0
git-indicators|lam|2.1.1
quicktype|qui|8.5.86
linter-xo|sam|2.1.3
json-schema-validator|tbe|0.1.0
better-align|wwm|1.1.6
markdown-all-in-one|yzh|1.0.5

(2 theme extensions excluded)

</details>
Reproduces without extensions