Convert all tests/*.tcl to use tcltest package

Almost all of the scripts under tests/*.tcl are legacy scripts that need to be renamed to be *.test and updated to use the tcltest package, so that they will be run automatically by "make test".

Additionally, the Github Actions for CI should be updated to run a lightweight webserver (possibly in a separate container?) so that all of the tests that access http://127.0.0.1/ can succeed.