Fix schema in viber locator hrefs from file-->editor

[ankostis]

In promnesia's search-results tab, links like file:///.ViberPC/123/viber.db do not work,
due to security (i guess, bc these urls work fine when pasted in a new tab).

The custom schema editor: offers a better UX,
since it gives the user the choice of which app to use to open the Viber's db-file (e.g. sqlitebrowser`),
when the mime-type is known to the OS (see the 1st resource, below).

These resources are relevant:

• install a sqlite mime-type handler
• change firefox handler
• karlicoss/open-in-editor custom handler

@karlicoss I want your tip about the mime-type handler to be included in the Viber docs; any idea where or how to include it?

[ankostis]

This PR fixes also a minor bug in the SQL-query, which previously fetched even overwritten due-to-edits viber messages.

[karlicoss]

Another way to achieve this is the post-index hook

promnesia/tests/indexer_test.py

Lines 284 to 303 in aded41c

	def HOOK(visit: Res[DbVisit]) -> Iterable[Res[DbVisit]]:
	# NOTE: might be a good idea to check that the visit is an exception first and yield it intact?
	nurl = visit.norm_url
	if 'page1' in nurl:
	yield visit._replace(norm_url='patched.com')
	elif 'page2' in nurl:
	None.boom # deliberately crash
	elif 'page3' in nurl:
	# just don't yield anything! it will be omitted
	pass
	elif 'page4' in nurl:
	# can emit multiple!
	yield visit
	yield visit
	elif 'page6' in nurl:
	# patch locator
	yield visit._replace(locator=Loc.make(title='some custom timte', href='/can/replace/original/path'))
	else:
	yield visit
	'''):

So e.g. you could do something like "if source is viber, then replace url etc etc".

But if you think it makes sense as a setting too, happy to merge.
I guess the whole thing with mime type configuration needs a bit more thinking. Maybe in general Promnesia could even offer multiple ways of opening the link (e.g. via sqlitebrowser and via web app (if it's possible, e.g. like for Telegram), etc, etc). Kind of related to #147 (comment)

[ankostis]

I think a better idea would be to make the url more configurable, e.g. store a print-pattern in the config,
but i believe we can merge this for the forseable future.