Fixes #7534.

For unmatched conditionals, C# returns null when asked for a matching
conditional directive, whereas VB returns a list with the single
unmatched directive in it. Incorporate checks for those into the
AbstractDirectiveTriviaBraceMatcher and add tests.

Lock files for csccore and vbccore

Use newest language version in scripting compilers

Vb interactive #r support

Cleanup of ForegroundNotificationServiceTests

Add *.vc.opendb created by VC++ to .gitignore

Only build Release packages if we have no dependency on pre-release packages

Updates SRM to 1.2.0-rc2-23608 and DSR to 1.0.7-beta1

This fixes two possible test bugs (see #7512):

- The notification fired but fired just after the clock was sync'd to the time server (test bug - don't use DateTime.Now/UtcNow)
- The notification fired exactly on 50 milliseconds (test bug)

It also helps us figure out whether the test failed because:

- The notification wasn't fired after 50 milliseconds (product bug)
- The notification didn't fire (product bug)

Add `CopyCode` operation to InteractiveWindow

Do not wait for all members to be completed to emit a compilation event for the container.

Provide a faster implementation of Fuzzy Searching for 'Add Using'.

Since nothing from standard-input is copied.

Add correct checks for ref/out arguments in delegate constructors for compat mode