chore: add remove-signer command, fix bugs, and update release notes

- Add registry admin remove-signer command to remove a signer and all their authorizations
- Fix remove_package_signer condition (is_some -> is_none) for correct not-found error
- Use log_err() instead of silently swallowing asset fetch errors
- Trim leading '#' from version in s9pk publish path
- Add --delete-removed to s3 sync in publish-deb.sh
- Expand v0.4.0 release notes with additional features
- Regenerate man pages and add i18n entries

core/man/start-cli/start-cli-registry-metrics-users.1

@@ -0,0 +1,22 @@
+.ie \n(.g .ds Aq \(aq
+.el .ds Aq '
+.TH start-cli-registry-metrics-users 1  "users " 
+.SH NAME
+start\-cli\-registry\-metrics\-users \- Count unique active users within a time range
+.SH SYNOPSIS
+\fBstart\-cli registry metrics users\fR [\fB\-\-after\fR] [\fB\-\-before\fR] [\fB\-\-format\fR] [\fB\-h\fR|\fB\-\-help\fR] 
+.SH DESCRIPTION
+Count unique active users within a time range
+.SH OPTIONS
+.TP
+\fB\-\-after\fR \fI<AFTER>\fR
+Start of time range (RFC 3339 timestamp)
+.TP
+\fB\-\-before\fR \fI<BEFORE>\fR
+End of time range (RFC 3339 timestamp)
+.TP
+\fB\-\-format\fR
+
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+Print help