Add embedded terminal tabs

[ph10w]

Overview

The standard Open Command Prompt action now opens cmd.exe in an Explorer++ tab. Elevated terminals remain external, with the existing command prompt used as a fallback when the embedded terminal is unavailable. Activating .bat or .cmd files opens a temporary terminal tab that closes when the script finishes.

Architecture

• Embeds Microsoft's HwndTerminal control and connects it to cmd.exe through ConPTY.
• Keeps terminal creation, process hosting, launch routing, message handling, clipboard access, and output parsing in focused terminal classes, minimizing changes to existing Explorer++ components.
• Loads the pinned Microsoft.Terminal.Control.dll dynamically from the application directory and includes it in portable and MSI packages with attribution.
• Defers ConPTY startup until the tab is visible and marshals terminal output to the UI thread, preserving the initial prompt when a terminal is reopened after exit.

Behavior

• Starts in the active folder, tracks cd changes in the tab title and tooltip, and closes interactive tabs when their command process exits.
• Supports terminal text copy and paste with surrounding control/whitespace cleanup, while preserving normal Explorer++ shortcuts outside terminal tabs.
• Provides Tab completion, Ctrl+Tab tab switching, scrollback with scrollbar and mouse wheel, Explorer++ font-size updates with Cascadia Mono, and a dedicated multi-size command-line icon.
• Integrates terminal content with tab focus, layout, taskbar previews, and safe initialization failure handling.

Checks performed

• Built Explorer++ and TestExplorer++ in Release|x64 with 0 warnings and 0 errors.
• Passed all 795 tests, including terminal clipboard/output parsing and locale-aware formatting coverage.
• Repeatedly verified open → exit → reopen, confirming that the path prompt appears immediately and remains usable.
• Verified interactive terminals, automatic batch execution/closure, and MSI XML/DLL paths. A local MSI build was not possible because WiX Toolset 3.11 is not installed.

[derceg]

Hi ph10w, this looks like a more significant change, so I appreciate the work you've put into it. I think it needs some justification, though. Is there a particular reason why running a terminal embedded in a tab is better than running it externally? Also, is Microsoft.Terminal.Control.dll designed to be used as a sort of public API in this way?