convmv: add dependencies to support additional encodings

This adds support for the following encodings:

```diff
diff --git a/a b/b
--- a/a
+++ b/b
@@ -4,8 +4,21 @@ AdobeSymbol
AdobeZdingbat
ascii
ascii-ctrl
+big5-1984
+big5-2003
big5-eten
big5-hkscs
+big5ext
+big5plus
+cccii
+cns11643-1
+cns11643-2
+cns11643-3
+cns11643-4
+cns11643-5
+cns11643-6
+cns11643-7
+cns11643-f
cp1006
cp1026
cp1047
@@ -46,15 +59,20 @@ cp949
cp950
dingbats
euc-cn
+euc-jisx0213
euc-jp
euc-kr
+euc-tw
gb12345-raw
+gb18030
gb2312-raw
gsm0338
hp-roman8
hz
+IMAP-UTF-7
iso-2022-jp
iso-2022-jp-1
+iso-2022-jp-3
iso-2022-kr
iso-8859-1
iso-8859-10
@@ -75,6 +93,8 @@ iso-ir-165
jis0201-raw
jis0208-raw
jis0212-raw
+jis0213-1-raw
+jis0213-2-raw
johab
koi8-f
koi8-r
@@ -109,9 +129,11 @@ nextstep
null
posix-bc
shiftjis
+shiftjisx0213
symbol
UCS-2BE
UCS-2LE
+unisys
UTF-16
UTF-16BE
UTF-16LE
```

pkgs/by-name/co/convmv/package.nix

···
   lib,
   stdenv,
   fetchzip,
+  makeWrapper,
   perl,
+  perlPackages,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
···
 
   strictDeps = true;
 
-  nativeBuildInputs = [ perl ];
+  nativeBuildInputs = [
+    makeWrapper
+    perl
+  ];
 
-  buildInputs = [ perl ];
+  buildInputs = [
+    perl
+    perlPackages.EncodeHanExtra
+    perlPackages.EncodeIMAPUTF7
+    perlPackages.EncodeJIS2K
+  ];
 
   makeFlags = [
     "PREFIX=${placeholder "out"}"
···
     '';
 
   dontPatchShebangs = true;
+
+  postFixup = ''
+    wrapProgram "$out/bin/convmv" --prefix PERL5LIB : "$PERL5LIB"
+  '';
 
   meta = with lib; {
     description = "Converts filenames from one encoding to another";