FIX: BBCode tag parser

Wasn't quite handling the cases where a closing bracket `]` was used in the value of one of the attributes.

```markdown
[chat quote=user channel="[broken]"]
```

Would not be correctly parsed because we would _greedily_ use the first `]` as the end of the tag even though it might be a valid character when inside proper quotes.

c39a4de139/app/assets/javascripts/discourse-markdown-it/src/features/bbcode-block.js (L62)

Re-wrote the `parseBBCodeTag` to properly handle the following cases

- A closing tag (aka `[/name]`) which are easy since they don't have any attributes
- An old `[quote=...]` format we used that doesn't uses quotes but still has various attributes of the form `key:value`
- All three valid BBCode opening tag formats we support
  - `[name]` without any attributes
  - `[name=foo]` with a default value
  - `[name foo=bar]` with some attributes

Ended up having to fix/rewrite the few bbcode rules that were using the `parseBBCodeTag` function, namely `d-wrap` and `discourse-local-dates`.

While working on this, I think I also found a way to get rid the of shims we had in place so that plugins could use the `parseBBCodeTag` function.

Reference - https://meta.discourse.org/t/having-a-right-bracket-in-a-channel-name-breaks-all-quotes-from-that-channel/308439

spec/lib/cooked_post_processor_spec.rb

@@ -1906,13 +1906,12 @@ RSpec.describe CookedPostProcessor do
     end
 
     context "with an unmodified quote" do
-      let(:cp) do
-        Fabricate(
-          :post,
-          raw:
-            "[quote=\"#{pp.user.username}, post: #{pp.post_number}, topic:#{pp.topic_id}]\nripe for quoting\n[/quote]\ntest",
-        )
-      end
+      let(:cp) { Fabricate(:post, raw: <<~MARKDOWN) }
+        [quote="#{pp.user.username}, post: #{pp.post_number}, topic:#{pp.topic_id}"]
+        ripe for quoting
+        [/quote]
+        test
+      MARKDOWN
 
       it "should not be marked as modified" do
         cpp.post_process_quotes
@@ -1921,13 +1920,12 @@ RSpec.describe CookedPostProcessor do
     end
 
     context "with a modified quote" do
-      let(:cp) do
-        Fabricate(
-          :post,
-          raw:
-            "[quote=\"#{pp.user.username}, post: #{pp.post_number}, topic:#{pp.topic_id}]\nmodified\n[/quote]\ntest",
-        )
-      end
+      let(:cp) { Fabricate(:post, raw: <<~MARKDOWN) }
+        [quote="#{pp.user.username}, post: #{pp.post_number}, topic:#{pp.topic_id}"]
+        modified
+        [/quote]
+        test
+      MARKDOWN
 
       it "should be marked as modified" do
         cpp.post_process_quotes
@@ -1936,13 +1934,12 @@ RSpec.describe CookedPostProcessor do
     end
 
     context "with external discourse instance quote" do
-      let(:external_raw) { <<~RAW.strip }
+      let(:cp) { Fabricate(:post, user: user_with_auto_groups, raw: <<~MARKDOWN.strip) }
         [quote="random_guy_not_from_our_discourse, post:2004, topic:401"]
         this quote is not from our discourse
         [/quote]
         and this is a reply
-        RAW
-      let(:cp) { Fabricate(:post, user: user_with_auto_groups, raw: external_raw) }
+      MARKDOWN
 
       it "it should be marked as missing" do
         cpp.post_process_quotes