feat: Implement build state tracking and interactive package specification creation

- Added StateTracker to manage build steps and allow resuming interrupted builds.
- Updated post_extract function to utilize StateTracker for patch and command execution.
- Introduced makefile.rs to handle building and installing packages via Makefile.
- Created interactive.rs for an interactive package specification creator with SHA256 computation for source URLs.
- Enhanced checksum verification to support multiple algorithms (SHA256, SHA512, MD5).
- Added example configuration files in contrib for system-wide and user-level Depot configurations.
- Updated tests to cover new functionality and ensure correctness of state tracking and interactive creation.

contrib/depot.toml

@@ -0,0 +1,24 @@
+# Example /etc/depot.toml - system-wide configuration for Depot
+
+[build]
+# Installation prefix for package builds
+prefix = "/usr"
+# Default compiler and archiver
+cc = "gcc"
+ar = "ar"
+
+[build.flags]
+# Basic compiler flags
+cflags = ["-O2"]
+# Append additional flags (demonstrates += append support)
+cflags += ["-g"]
+
+# Linker flags
+ldflags = ["-Wl,-O1"]
+
+# Target architecture short name (CARCH). Defaults to host arch if unset.
+carch = "x86_64"
+
+# Target triples (optional)
+#chost = "x86_64-pc-linux-gnu"
+#cbuild = "x86_64-pc-linux-gnu"