fix(uri): uri_encode encodes brackets incorrectly for RFC2732 #31284

**Problem:**
The brackets in the RFC2732 regular expression are currently unescaped,
causing them to be misinterpreted as special characters denoting
character groups rather than as literal characters.

**Solution:**
Escape the brackets.
Fix #31270

(cherry picked from commit 442d338cb5)

runtime/lua/vim/uri.lua

@@ -15,7 +15,7 @@ local PATTERNS = {
   rfc2396 = "^A-Za-z0-9%-_.!~*'()",
   -- RFC 2732
   -- https://tools.ietf.org/html/rfc2732
-  rfc2732 = "^A-Za-z0-9%-_.!~*'()[]",
+  rfc2732 = "^A-Za-z0-9%-_.!~*'()%[%]",
   -- RFC 3986
   -- https://tools.ietf.org/html/rfc3986#section-2.2
   rfc3986 = "^A-Za-z0-9%-._~!$&'()*+,;=:@/",

test/functional/lua/uri_spec.lua

@@ -252,4 +252,12 @@ describe('URI methods', function()
       end
     )
   end)
+
+  describe('encode to uri', function()
+    it('rfc2732 including brackets', function()
+      exec_lua("str = '[:]'")
+      exec_lua("rfc = 'rfc2732'")
+      eq('[%3a]', exec_lua('return vim.uri_encode(str, rfc)'))
+    end)
+  end)
 end)