update swagger ms-rest to latest versions

[tomlm]

Fixes: #665

Update AutoRest to latest AutoRest and latest Typescript generator

     "@microsoft.azure/autorest.typescript": "^2.3.3",
    "autorest": "^2.0.4283"

Updated ms-rest to
"@azure/ms-rest-js": "^1.2.6",

Fixed Agent string as per discussion in forum.

[coveralls]

Pull Request Test Coverage Report for Build 2576

• 30 of 33 (90.91%) changed or added relevant lines in 11 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 82.213%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/botbuilder/src/botFrameworkAdapter.ts	1	2	50.0%
libraries/botframework-connector/src/tokenApi/tokenApiClientContext.ts	1	3	33.33%

Totals
Change from base Build #1780:	0.01%
Covered Lines:	2705
Relevant Lines:	3165

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💛 - Coveralls