Dafny 3.8.1

• feat: Support for the {:opaque} attibute on const (#2545)
• feat: Support for plugin-based code actions on the IDE (#2021)
• fix: Fixed a crash when parsing newtype in the parser (#2649)
• fix: Added missing error reporting position on string prefix check (#2652)
• fix: Prevent LSP server from exiting when a crash occurs (#2664)
• fix: Fix bug where LSP server would not show diagnostics that referred to included files (#2664)
• fix: Check all compiled expressions to be compilable (#2641)
• fix: Better messages on hovering failing postconditions in IDE (#2654)
• fix: Better error reporting on counter-examples if an option is not provided (#2650)