[PORT]Make template name format consistent with function name format

[Danieladu]

Original issue: microsoft/botbuilder-dotnet#3942
close: #2258
The function name's format cannot cover all template name's formats.

The valid format of template name is

start with letter/number/_ and can only contains letter/number/./_

And the valid format of function name should meet

foreach(var part in expression.split('.')) 
{
    // part should start with letter/_ and can only contains letter/number/_
}

So, in some cases, user use template evaluation in expression with the "gap" format would throw exception.

Here is the remedy that disables the name that begins with number in each part of the split result from dot(.).

Now, the valid format of template name should be :

foreach(var part in expression.split('.')) 
{
    // part should start with letter/_ and can only contains letter/number/_
}

Same with the expression function name.

[coveralls]

Pull Request Test Coverage Report for Build 132619

• 3 of 3 (100.0%) changed or added relevant lines in 2 files are covered.
• 9 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.07%) to 80.286%

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Files with Coverage Reduction	New Missed Lines	%
libraries/botframework-streaming/src/webSocket/webSocketTransport.ts	2	80.65%
libraries/botframework-streaming/src/webSocket/webSocketServer.ts	7	66.67%

Totals
Change from base Build 132473:	-0.07%
Covered Lines:	12691
Relevant Lines:	15092

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💛 - Coveralls