[eacsl] Move demo and known bugs in an "examples" folder

src/plugins/e-acsl/examples/demo/.gitignore

src/plugins/e-acsl/examples/demo/TODO

src/plugins/e-acsl/examples/demo/alone.sh

src/plugins/e-acsl/examples/demo/clean.sh

src/plugins/e-acsl/examples/demo/compile.sh

src/plugins/e-acsl/examples/demo/custom_assert.c

src/plugins/e-acsl/examples/demo/demo.c

src/plugins/e-acsl/examples/demo/demo.sh

src/plugins/e-acsl/examples/demo/load.sh

src/plugins/e-acsl/examples/demo/my_e_acsl.c

src/plugins/e-acsl/examples/demo/pow.c

src/plugins/e-acsl/examples/demo/run_demo.sh

src/plugins/e-acsl/examples/demo/run_script.sh

src/plugins/e-acsl/examples/demo/script.ml

src/plugins/e-acsl/examples/known_bugs/README

src/plugins/e-acsl/examples/known_bugs/bts1354_logical_at.i

...plugins/e-acsl/examples/known_bugs/bts1379_read_address.c

...s/e-acsl/examples/known_bugs/bts1395_recursive_function.i

...examples/known_bugs/bts1636_memory_leak_literal_strings.i

src/plugins/e-acsl/examples/known_bugs/let-alias.c