sources.browser_new: initial work on using HPI + seanbreckenridge/bro…

…wserexport

later will rename to browser, and implement defensive fallback onto browser_old

adapted from https://github.com/seanbreckenridge/promnesia/blob/master/promnesia_sean/sources/browsing.py

related: #339

Old vs new modules produce almost identical results (tested on various chrome & firefox databases)
There are some minor differences vs the old module:

- old database timestamps end with +00:00 UTC, new ones with +00:00 -- likely because browserexport is using timezone.utc instead of pytz
- previously locator was pointing at the database file, now it's pointing at the URL

  I guess it's not necessarily in the 'spirit' of locator field, but on the other hand, not that it's very useful to point to an sqlite file either.
  Perhaps later it could be in some sort of extra debug field instead.

src/promnesia/sources/browser_new.py

@@ -0,0 +1,22 @@
+from typing import Optional
+
+from promnesia.common import Results, Visit, Loc, Second
+
+
+def index() -> Results:
+    from . import hpi
+    from my.browser.all import history
+
+    for v in history():
+        desc: Optional[str] = None
+        duration: Optional[Second] = None
+        metadata = v.metadata
+        if metadata is not None:
+            desc = metadata.title
+            duration = metadata.duration
+        yield Visit(
+            url=v.url,
+            dt=v.dt,
+            locator=Loc(title=desc or v.url, href=v.url),
+            duration=duration,
+        )