Sort jsdoc parameter suggestions by argument position

From https://github.com/Microsoft/vscode/issues/35124

TypeScript Version: 2.7.0-dev.20171116

Code

For the code:

/**
 * @param |
 */
function foo(z, a) {}

Trigger completions at the | after @param

Expected behavior:
z is returned first, followed by a. The sortText can be used for this

Actual behavior:
a and z are returned with sort orders weights:

[Trace  - 11:33:07 PM] Sending request: completions (176). Response expected: yes. Current queue length: 0
Arguments: {
    "file": "/Users/matb/projects/san/y.ts",
    "line": 2,
    "offset": 11,
    "includeExternalModuleExports": true
}
[Trace  - 11:33:07 PM] Response received: completions (176). Request took 2 ms. Success: true 
Result: [
    {
        "name": "a",
        "kind": "parameter",
        "kindModifiers": "",
        "sortText": "0"
    },
    {
        "name": "z",
        "kind": "parameter",
        "kindModifiers": "",
        "sortText": "0"
    }
]

JSDoc @param の候補に対応する TypeScript language service の補完エントリーポイントから始め、function foo(z, a) の例を再現します。パラメーターが引数の位置に従うように補完の順序を調整し、その後、z が a より前に返され、sortText がこの順序を反映していることを確認します。