feat: add JSONL support to JSON lexer (#1262)

### Description
This PR adds support for JSON Lines (JSONL) to the existing JSON lexer.

Because the existing JSON lexer already handles repeating objects
natively, this implementation simply maps the \`jsonl\` file extension,
alias, and mime type to the \`JSON\` lexer configuration without needing
any underlying state machine changes.

Inspired by walles/moor#407.

### Changes
* **Alias added:** \`jsonl\`
* **File extension added:** \`*.jsonl\`
* **MIME type added:** \`application/jsonl\`
* **Tests:** Added \`jsonl.actual\` and \`jsonl.expected\` validation
files to ensure tokens are correctly extracted across newlines in
\`.jsonl\` files.

### Testing
Ran \`go test ./lexers -run TestLexers\` locally to verify that JSON
Lines objects format accurately and consistently.

Author: walles

lexers/embedded/json.xml

@@ -2,12 +2,15 @@
   <config>
     <name>JSON</name>
     <alias>json</alias>
+    <alias>jsonl</alias>
     <filename>*.json</filename>
+    <filename>*.jsonl</filename>
     <filename>*.jsonc</filename>
     <filename>*.json5</filename>
     <filename>*.avsc</filename>
     <filename>.luaurc</filename>
     <mime_type>application/json</mime_type>
+    <mime_type>application/jsonl</mime_type>
     <dot_all>true</dot_all>
     <not_multiline>true</not_multiline>
   </config>

lexers/testdata/jsonl.actual

@@ -0,0 +1,2 @@
+{"name": "Alice"}
+{"name": "Bob"}

lexers/testdata/jsonl.expected

@@ -0,0 +1,16 @@
+[
+  {"type":"Punctuation","value":"{"},
+  {"type":"NameTag","value":"\"name\""},
+  {"type":"Punctuation","value":":"},
+  {"type":"Text","value":" "},
+  {"type":"LiteralStringDouble","value":"\"Alice\""},
+  {"type":"Punctuation","value":"}"},
+  {"type":"Text","value":"\n"},
+  {"type":"Punctuation","value":"{"},
+  {"type":"NameTag","value":"\"name\""},
+  {"type":"Punctuation","value":":"},
+  {"type":"Text","value":" "},
+  {"type":"LiteralStringDouble","value":"\"Bob\""},
+  {"type":"Punctuation","value":"}"},
+  {"type":"Text","value":"\n"}
+]

test.jsonl

@@ -0,0 +1,2 @@
+{"name": "Alice"}
+{"name": "Bob"}