Warn when v5 sees -brute / bruteforce.wordlists (#1122)

[ChrisJr404]

Summary

Refs #1122.

@je-bugshell pointed out that v5 still parses the `-brute` CLI flag and the `bruteforce.wordlists` YAML key — `cfg.BruteForcing` and `cfg.Wordlist` get populated from CLI (`internal/enum/cli.go:451`) and YAML (`config/brute.go`), respectively — but nothing in `engine/` reads `cfg.Wordlist`. The only plugin in `engine/plugins/brute/` is `alterations.go`, which uses `cfg.AltWordlist` (a separate field), and the `BruteForcing` toggle is reused there to mean "also do alterations." A v4 user expects `-brute -w wordlist.txt` to generate `.example.com` guesses; in v5 they currently get nothing of the sort.

The issue body offers two paths:

1. Port the v4 wordlist brute-force script to a v5 plugin.
2. If a port isn't on the roadmap, log a clear warning so users aren't silently getting less than they asked for.

I went with path 2 here, since the porting question is yours to answer. @je-bugshell explicitly offered (1) as a follow-up if you decide to take it; this PR doesn't preempt that.

Change

• New `warnUnsupportedConfig` helper in `internal/enum/cli.go`, called from `CLIWorkflow` immediately after `argsAndConfig`. It emits a single yellow line on `color.Error` if both `cfg.BruteForcing` and `cfg.Wordlist` are set, telling the user wordlist brute forcing isn't implemented in v5 yet, that `-brute` currently only gates FQDN alterations, and pointing at issue v5: -brute flag and bruteforce.wordlists config are accepted but never used #1122 for status.
• No warning is emitted when only one of the two is set (a YAML wordlist alone with no `-brute`, or `-brute` with no wordlist) so existing alterations-only workflows aren't noisy.

Test

`internal/enum/cli_test.go` (new file) — `TestWarnUnsupportedConfig` covers 5 cases:

• nil config → no warning
• empty config → no warning
• `-brute` only → no warning
• wordlist only → no warning
• `-brute` + wordlist → warning emitted, references issue v5: -brute flag and bruteforce.wordlists config are accepted but never used #1122

$ go test ./internal/enum/ -run TestWarnUnsupportedConfig -v
=== RUN   TestWarnUnsupportedConfig
--- PASS: TestWarnUnsupportedConfig (0.00s)
ok  	github.com/owasp-amass/amass/v5/internal/enum	0.011s

`go vet ./internal/enum/...` is clean.

Notes

• I did not add this to `oam_enum` or other binaries — only `amass enum` reaches `CLIWorkflow`. If you'd like the warning surfaced from `oam_enum` too, happy to lift it into a shared helper.
• Once the porting question is answered, this warning is one line to remove (or to repoint at a "deprecated, see X" message). It's intentionally cheap to undo.