chore(solidity): add highlight queries (#12102)

Add highlights for `hex` and `unicode` string prefixes and YUL booleans

runtime/queries/solidity/highlights.scm

@@ -12,6 +12,8 @@
  (unicode_string_literal)
  (yul_string_literal)
 ] @string
+(hex_string_literal "hex" @string.special.symbol)
+(unicode_string_literal "unicode" @string.special.symbol)
 [
  (number_literal)
  (yul_decimal_number)
@@ -20,6 +22,7 @@
 [
  (true)
  (false)
+ (yul_boolean)
 ] @constant.builtin.boolean
 
 (comment) @comment