Instead of using an `import_map.json` file to define the versions for
dependencies, they are now defined directly within the import. Since the
`import_map.json` file should not be used anymore and instead a
`deno.json` file per function should be used, we decided to define them
directly with the code. The overhead compared to a `deno.json` file per
function shouldn't be that large and it makes using functions in a
self-hosted setup easier.
The log level is now configurable, via the `FEEDDECK_LOG_LEVEL`
environment variable. The environment variable can have the following
values: `debug`, `info`, `warning` or `error`.
With this change we also only log the response when getting and parsing
the feed fails when the log level is set to `debug`, also when the
actual message is still an error. This should reduce the noice in the
logs a lot and allows us to specially turn this on while debugging.