Add rule for disallow collections keyword in favor of FQCN

[jcgruenhage]

https://ansible-lint.readthedocs.io/rules/fqcn/ includes a section about the collections keyword being something to avoid in favor of using FQCNs instead. If we have stuff like this in the docs, we should also have a lint for it.

[jcgruenhage]

In case this is something that's wanted, I've already adjusted the rule locally to do this:

From d540e3a716dd8a0900c0d6a1bdc244241114e9a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Christian=20Gr=C3=BCnhage?=
 <[email protected]>
Date: Thu, 24 Nov 2022 14:56:27 +0100
Subject: [PATCH] feat: extend fqcn rule to complain on `collections` keyword

---
 src/ansiblelint/rules/fqcn.md |  1 +
 src/ansiblelint/rules/fqcn.py | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/ansiblelint/rules/fqcn.md b/src/ansiblelint/rules/fqcn.md
index 18fb917b..c949d51b 100644
--- a/src/ansiblelint/rules/fqcn.md
+++ b/src/ansiblelint/rules/fqcn.md
@@ -10,6 +10,7 @@ The `fqcn` rule has the following checks:
 - `fqcn[action]` - Use FQCN for module actions, such ...
 - `fqcn[action-core]` - Checks for FQCNs from the `ansible.legacy` or `ansible.builtin` collection.
 - `fqcn[canonical]` - You should use canonical module name ... instead of ...
+- `fqcn[keyword]` - You shouldn't use the `collections` keyword, use the FQCNs instead.
 
 ```{note}
 In most cases you should declare the `ansible.builtin` collection for internal Ansible actions.
diff --git a/src/ansiblelint/rules/fqcn.py b/src/ansiblelint/rules/fqcn.py
index 106fd0c8..593ce37e 100644
--- a/src/ansiblelint/rules/fqcn.py
+++ b/src/ansiblelint/rules/fqcn.py
@@ -7,6 +7,7 @@ from typing import Any
 
 from ansible.plugins.loader import module_loader
 
+from ansiblelint.constants import LINE_NUMBER_KEY
 from ansiblelint.errors import MatchError
 from ansiblelint.file_utils import Lintable
 from ansiblelint.rules import AnsibleLintRule, RulesCollection
@@ -159,6 +160,20 @@ class FQCNBuiltinsRule(AnsibleLintRule):
                     )
         return result
 
+    def matchplay(self, file: Lintable, data: dict[str, Any]) -> list[MatchError]:
+        if file.kind != "playbook":
+            return []
+        if "collections" in data:
+            return [
+                self.create_matcherror(
+                    message="Don't use collections keyword.",
+                    linenumber=data[LINE_NUMBER_KEY],
+                    tag="fqcn[keyword]",
+                    filename=file,
+                )
+            ]
+        return []
+
 
 # testing code to be loaded only with pytest or when executed the rule file
 if "pytest" in sys.modules:
-- 
2.38.1