Generate changelog / Add .NET 12 runtime and toolchain support (#3253) Add .NET 12 monikers, cached runtimes and toolchains including composite ReadyToRun and Mono WebAssembly. Update development defaults and templates, and cover runtime parsing and CLI resolution. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Generate changelog / Add .NET 12 runtime and toolchain support (#3253) Add .NET 12 monikers, cached runtimes and toolchains including composite ReadyToRun and Mono WebAssembly. Update development defaults and templates, and cover runtime parsing and CLI resolution. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> #609