p1: /v2/scrape, /v1/fetch, auth, CLI, contract tests

Single Fetcher.Fetch on the Guard that holds DenyPrefixes. skipTlsVerification
is ignored. No 502. keys add writes the secret only to --out. Release binary
has no -test-allow-prefix.

vendor/github.com/pelletier/go-toml/v2/SECURITY.md

@@ -0,0 +1,16 @@
+# Security Policy
+
+## Supported Versions
+
+| Version    | Supported          |
+| ---------- | ------------------ |
+| Latest 2.x | :white_check_mark: |
+| All 1.x    | :x:                |
+| All 0.x    | :x:                |
+
+## Reporting a Vulnerability
+
+Email a vulnerability report to `security@pelletier.codes`. Make sure to include
+as many details as possible to reproduce the vulnerability. This is a
+side-project: I will try to get back to you as quickly as possible, time
+permitting in my personal life. Providing a working patch helps very much!