fix: commenting issues on gas lexer (#1247)

Fixes commenting issues in the GAS lexer and adds tests.

- Adds tests for `gas`
- Changes comment regex in 3 states: `directive-args`,
`instruction-args`, `whitespace`

**Fixes #447**  
`@|!` - Adds comment prefixes
ARM  `@`
Motorola 68k `|`
SuperH `!`

**Fixes #1246**  
`\n` -> `\n?` - makes trailing newline optional so final-line comments
are highlighted
`.*?` -> `.*` - removed unnecessary lazy quantifier

<img width="751" height="304" alt="image"
src="https://github.com/user-attachments/assets/9fd38bf2-6ee7-4656-9ecd-a161d57a7714"
/>

Author: monjiapawne

lexers/embedded/gas.xml

@@ -56,7 +56,7 @@
         <token type="Text"/>
         <pop depth="1"/>
       </rule>
-      <rule pattern="([;#]|//).*?\n">
+      <rule pattern="([;#@|!]|//).*\n?">
         <token type="CommentSingle"/>
         <pop depth="1"/>
       </rule>
@@ -114,7 +114,7 @@
         <token type="Text"/>
         <pop depth="1"/>
       </rule>
-      <rule pattern="([;#]|//).*?\n">
+      <rule pattern="([;#@|!]|//).*\n?">
         <token type="CommentSingle"/>
         <pop depth="1"/>
       </rule>
@@ -139,7 +139,7 @@
       <rule pattern="\s+">
         <token type="Text"/>
       </rule>
-      <rule pattern="([;#]|//).*?\n">
+      <rule pattern="([;#@|!]|//).*\n?">
         <token type="CommentSingle"/>
       </rule>
       <rule pattern="/[*][\w\W]*?[*]/">

lexers/testdata/gas.actual

@@ -0,0 +1,13 @@
+# Returns bit 5 of a number.
+.globl _start
+.section .text
+_start:
+    mov $0, %rdi            # zero rdi
+    mov $0b00100011, %rcx   // input value
+    test $0b00010000, %rcx  /* bit mask, set zero flag */
+    jz final                ! if zero jump out
+    mov $1, %rdi            @ else, the test wasn't zero, set output to 1
+
+final:
+    mov $60, %rax           | set exit syscall
+    syscall                 # make syscall

lexers/testdata/gas.expected

@@ -0,0 +1,69 @@
+[
+  {"type":"CommentSingle","value":"# Returns bit 5 of a number.\n"},
+  {"type":"NameAttribute","value":".globl"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":"_start"},
+  {"type":"Text","value":"\n"},
+  {"type":"NameAttribute","value":".section"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":".text"},
+  {"type":"Text","value":"\n"},
+  {"type":"NameLabel","value":"_start:"},
+  {"type":"Text","value":"\n    "},
+  {"type":"NameFunction","value":"mov"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":"$0"},
+  {"type":"Punctuation","value":","},
+  {"type":"Text","value":" "},
+  {"type":"NameVariable","value":"%rdi"},
+  {"type":"Text","value":"            "},
+  {"type":"CommentSingle","value":"# zero rdi\n"},
+  {"type":"Text","value":"    "},
+  {"type":"NameFunction","value":"mov"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":"$0b00100011"},
+  {"type":"Punctuation","value":","},
+  {"type":"Text","value":" "},
+  {"type":"NameVariable","value":"%rcx"},
+  {"type":"Text","value":"   "},
+  {"type":"CommentSingle","value":"// input value\n"},
+  {"type":"Text","value":"    "},
+  {"type":"NameFunction","value":"test"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":"$0b00010000"},
+  {"type":"Punctuation","value":","},
+  {"type":"Text","value":" "},
+  {"type":"NameVariable","value":"%rcx"},
+  {"type":"Text","value":"  "},
+  {"type":"CommentMultiline","value":"/* bit mask, set zero flag */"},
+  {"type":"Text","value":"\n    "},
+  {"type":"NameFunction","value":"jz"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":"final"},
+  {"type":"Text","value":"                "},
+  {"type":"CommentSingle","value":"! if zero jump out\n"},
+  {"type":"Text","value":"    "},
+  {"type":"NameFunction","value":"mov"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":"$1"},
+  {"type":"Punctuation","value":","},
+  {"type":"Text","value":" "},
+  {"type":"NameVariable","value":"%rdi"},
+  {"type":"Text","value":"            "},
+  {"type":"CommentSingle","value":"@ else, the test wasn't zero, set output to 1\n"},
+  {"type":"Text","value":"\n"},
+  {"type":"NameLabel","value":"final:"},
+  {"type":"Text","value":"\n    "},
+  {"type":"NameFunction","value":"mov"},
+  {"type":"Text","value":" "},
+  {"type":"NameConstant","value":"$60"},
+  {"type":"Punctuation","value":","},
+  {"type":"Text","value":" "},
+  {"type":"NameVariable","value":"%rax"},
+  {"type":"Text","value":"           "},
+  {"type":"CommentSingle","value":"| set exit syscall\n"},
+  {"type":"Text","value":"    "},
+  {"type":"NameFunction","value":"syscall"},
+  {"type":"Text","value":"                 "},
+  {"type":"CommentSingle","value":"# make syscall"}
+]