Fix method UserAgentClientMinorVersion

Fix UserAgentClientMinorVersion. UserAgent may not always have the patchversion. So, need to parse for minor version slightly differently.
Only added comments to function 'UserAgentClientMajorVersion'

Ran the following tests

DECLARE		@UserAgent1 nvarchar(4000) = 'NuGet Command Line/2.8.4 (Microsoft Windows NT 6.3.9600.0)'
DECLARE		@UserAgent2 nvarchar(4000) = 'NuGet Command Line/2.8 '
DECLARE		@UserAgent3 nvarchar(4000) = 'NuGet Command Line/2.8 (Microsoft Windows NT 6.3.9600.0)'
DECLARE		@UserAgent4 nvarchar(4000) = 'NuGet Command Line/2.8'

SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent1)
SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent2)
SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent3)
SELECT		[dbo].[UserAgentClientMinorVersion-Test](@UserAgent4)

SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent1)
SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent2)
SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent3)
SELECT		[dbo].[UserAgentClientMajorVersion-Test](@UserAgent4)
Stretch goal: refactor this statement to be readable. If it means breaking the statement up into multiple statements, that's cool.  This is pretty hard to follow here though.  And it seems like we should be able to identify the space after the number and know to terminate there, rather than relying on the open parens.