Add `clean.sh` to all applications to remove build artifacts

[vidyalakshmir]

Description

Currently, we lack a standardized way to clean up the artifacts produced during the build process for our applications. We need to introduce a clean.sh script to each application directory that will comprehensively remove all generated files, intermediary build files, and staged assets.

Changes required

• Add clean.sh: Create a clean.sh script in each application directory.
• Clear staged files: Remove all files staged to the build/$app directory.
• Remove intermediary files: Clean up all intermediary build files residing in the $app folder or within the build/ folder including:
  • .wasm files
  • .opt.wasm files
  • .opt.cwasm files
  • Object (.o) files
  • Any other standard files/folders produced as a result of the build.
• Remove generated Makefiles: If a configure script is invoked during the build and generates a Makefile, the cleanup script must remove this generated Makefile.