* Remove the second appearance of server name in TargetName property
* Replace slash with colon as database name separator in TargetName to avoid ambiguity
Fixes#968
[SQL Assessment API](https://docs.microsoft.com/en-us/sql/sql-assessment-api/sql-assessment-api-overview) provides a mechanism to evaluate the configuration
of SQL Server for best practices. SQL Assessment API gives a list
of recommended actions to improve SQL Server performance or security.
The SQL Assessment service is used by the expected SQL Assessment
feature of Azure Data Studio.
SqlAssessmentService forwards JSONRPC calls to SQL Assessment engine
and wraps results as a response.
`assessment/getAssessmentItems` returns a set of checks
applicable to a given target.
`assessment/invoke` returns a set of recommendations
for improving SQL Server instance or database configurations.
`assessment/generateScript` returns a T-SQL script for storing
an assessment result set to a SQL data table.
FileUtils.TestServerNamesDefaultFileName_get uses '… + @"\\" + …'
construct to build the default path for the test server names file.
While escaping a backslash in a verbatim string is a typo, the
approach was error-prone. Replace string manipulation and environment
variables magic with calls to well-tested library functions.
GetSettingFileContent() displays a message on switching to VS Code
settings when SQL connection instances were configured.
Move the message to the branch for the absent test configuration file.
Aleksei Guzev