quick fix for #3753

[VladDBA]

This fix doesn't address the output object names, but I can tackle those those if needed as well.

Behavior with this fix:

/*These work*/
EXEC sp_BlitzIndex;
EXEC sp_BlitzIndex @GetAllDatabases = 1, @Mode = 0;
EXEC sp_BlitzIndex @GetAllDatabases = 1, @Mode = 1;
EXEC sp_BlitzIndex @GetAllDatabases = 1, @Mode = 2;
EXEC sp_BlitzIndex @GetAllDatabases = 1, @Mode = 3;
EXEC sp_BlitzIndex @GetAllDatabases = 1, @Mode = 4;
EXEC sp_BlitzIndex @DatabaseName = 'StackOverflow', @TableName = 'Users'; 
EXEC sp_BlitzIndex @DatabaseName = 'StackOverflow', @TableName = 'dbo.Users';
EXEC sp_BlitzIndex @DatabaseName = 'StackOverflow', @TableName = '[dbo].Users';
EXEC sp_BlitzIndex @DatabaseName = 'StackOverflow', @TableName = '[dbo].[Users]';
EXEC sp_BlitzIndex 'StackOverflow.dbo.Users';


/*all following variations work*/
EXEC sp_BlitzIndex @DatabaseName = '[Testing.1.2]';
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2'; 
EXEC sp_BlitzIndex '[Testing.1.2].[Very.Bad.Schema].[Very.Bad.Idea]'
EXEC sp_BlitzIndex @DatabaseName = '[Testing.1.2]', @TableName = '[Very.Bad.Schema].[Very.Bad.Idea]' 
EXEC sp_BlitzIndex @DatabaseName = '[Testing.1.2]', @SchemaName = 'Very.Bad.Schema', @TableName = 'Very.Bad.Idea'
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2', @SchemaName = 'Very.Bad.Schema', @TableName = 'Very.Bad.Idea'
EXEC sp_BlitzIndex @DatabaseName = '[Testing.1.2]', @SchemaName = '[Very.Bad.Schema]', @TableName = '[Very.Bad.Idea]'
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2', @SchemaName = '[Very.Bad.Schema]', @TableName = '[Very.Bad.Idea]'
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2', @SchemaName = '[Very.Bad.Schema]', @TableName = 'Very.Bad.Idea'
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2', @TableName = '[Very.Bad.Idea]'; /*will not work if the same table name exists in multiple schemas*/
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2', @TableName = 'Very.Bad.Idea'; /*will not work if the same table name exists in multiple schemas*/

/*This does not work due to not finding schema or object (at this point, this is the lesser evil) */
EXEC sp_BlitzIndex @DatabaseName = '[Testing.1.2]', @TableName = 'Very.Bad.Schema.Very.Bad.Idea';
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2', @TableName = '[Very.Bad.Schema].Very.Bad.Idea'; 
EXEC sp_BlitzIndex @DatabaseName = 'Testing.1.2', @TableName = 'Very.Bad.Schema.[Very.Bad.Idea]';


/*It doesn't error out, but it outputs Mode = 0 for the database in which sp_BlitzIndex lives, completely ignoring the input*/
EXEC sp_BlitzIndex 'Testing.1.2.Very.Bad.Schema.Very.Bad.Idea';

[BrentOzar]

Thanks for the pull request! Looks good, merging into the dev branch, will get a release out tonight with it.