Implements task-21195.

Fixes #21143.

added executable bootstrap script, removed metrics_checks.xml.

Adapted from Onionoo's #20712.

This test currently breaks and will be fixed in #20714.

Some bridges report these hidserv-* lines, probably shortly after
switching from relay to bridge mode.  There's nothing particular
sensitive in these lines that would reveal the bridge IP address or
location.  We can simply copy them over like the other statistics
lines.

Fixes #20714.

as it is not part of the webapp files.
Adapted path in INSTALL.md to match the new location.

Contains many suggestions by iwakeh.

Implements #20380.

by grouping them according to marker and host.

Implements task-19831.

these temporary files after sync.

and a sync-marker test.

i.e. files starting with "." or ending with ".tmp".

ReferenceChecker had to be disabled (cf. #20335).
Added persistence and sync package as well as tests and test resources.

Some of these paths might work okay if configured relative to the
working directory.  But it's safer to just use absolute paths.  This
works fine on the main CollecTor instance.

Fixes #20179.

DownloadCurrentConsensus,
DownloadCurrentMicrodescConsensus,
DownloadCurrentVotes,
DownloadMissingServerDescriptors,
DownloadMissingExtraInfoDescriptors,
and DownloadMissingMicrodescriptors

Each was replaced by hard-coded 'true'.

Implements #20408.