Improve language consistency add-on logs

[nijel]

Describe the problem

Right now the add-ons log only contain information about the add-on being executed. While this is useful, it would be useful to contain more information.

Let's start with the language consistency add-on. The log should include:

• Information on added languages
• Information on languages which could not be added

Describe the solution you would like

The background task should extend/append the log entry.

Describe alternatives you have considered

No response

Screenshots

No response

Additional context

Probably all logging from the task should make it into add-on log:

weblate/weblate/addons/tasks.py

Lines 77 to 115 in 9db0980

	@app.task(
	trail=False,
	autoretry_for=(WeblateLockTimeoutError,),
	retry_backoff=600,
	retry_backoff_max=3600,
	)
	def language_consistency(
	addon_id: int, language_ids: list[int], project_id: int
	) -> None:
	addon = Addon.objects.get(pk=addon_id)
	project = Project.objects.get(pk=project_id)
	languages = Language.objects.filter(id__in=language_ids)
	request = HttpRequest()
	request.user = addon.addon.user
	for component in project.component_set.iterator():
	missing = languages.exclude(
	Q(translation__component=component) | Q(component=component)
	)
	if not missing:
	continue
	component.commit_pending("language consistency", None)
	for language in missing:
	new_lang = component.add_new_language(
	language,
	request,
	send_signal=False,
	create_translations=False,
	)
	if new_lang is None:
	component.log_warning(
	"could not add %s language for language consistency", language
	)
	else:
	new_lang.log_info("added for language consistency")
	try:
	component.create_translations_task()
	except FileParseError as error:
	component.log_error("could not parse translation files: %s", error)