refactor(frontends/lean): rename lean.lua to lean.lua.h

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(build): copy extra files to bin directory

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(util/script_state): add 'import' command to Lua, it import files from the LEAN_PATH

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
chore(frontends/lua/lean.lua.h): fix style warnings

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>