Update to Amaranth 0.5

[miek]

Work-in-progress on updating to Amaranth 0.5:

• Replace uses of amaranth.hdl.Memory with amaranth.lib.memory.Memory
• Remove uses of Signal.width
• Replace uses of reset= with init=
• Remove uses of Pin
• Update tests to remove uses of add_sync_process
• ...

[miek]

I think this is ready for review now.

I decided to drop the synchronize helper in favour of less magic and because it was tied pretty closely to Pin/Record which are going away. Most of its uses were from unmaintained examples that depended on old hardware, that I've also removed.

I also decided to skip porting away from add_sync_process for now as refactoring all the tests is going to be a big job, and I'd rather leave that to a follow-up PR, so the test runs will have a deprecation warning relating to that.

Otherwise it's all fairly simple changes from the list here: https://amaranth-lang.org/docs/amaranth/latest/changes.html#migrating-from-version-0-4

[zyp]

It's not necessary to explicitly construct a Shape here, any shape-like can be used, and since that includes integers, you can simply just pass shape=self.sample_width. shape is effectively a superset of the old width argument.

This goes for the other Memory instances in this commit as well.

[miek]

Fixed, thanks!