Fix not FHS paths

Create explicit nix path replacement of hard coded FHS paths for pandoc and nodejs.

pkgs/applications/editors/rstudio/default.nix

@@ -128,6 +128,7 @@ in
       ./clang-location.patch
       ./use-system-node.patch
       ./fix-resources-path.patch
+      ./pandoc-nix-path.patch
     ];
 
     postPatch = ''
@@ -137,14 +138,14 @@ in
         --replace 'SOCI_LIBRARY_DIR "/usr/lib"' 'SOCI_LIBRARY_DIR "${soci}/lib"'
 
       substituteInPlace src/gwt/build.xml \
-        --replace '/usr/bin/node' '${nodejs}/bin/node'
+        --replace '@node@' ${nodejs}
 
       substituteInPlace src/cpp/core/libclang/LibClang.cpp \
         --replace '@libclang@' ${llvmPackages.libclang.lib} \
         --replace '@libclang.so@' ${llvmPackages.libclang.lib}/lib/libclang.so
 
       substituteInPlace src/cpp/session/include/session/SessionConstants.hpp \
-        --replace "bin/pandoc" "${pandoc}/bin/pandoc"
+        --replace '@pandoc@' ${pandoc}/bin/pandoc
     '';
 
     hunspellDictionaries = with lib; filter isDerivation (unique (attrValues hunspellDicts));

pkgs/applications/editors/rstudio/pandoc-nix-path.patch

@@ -0,0 +1,11 @@
+--- a/src/cpp/session/include/session/SessionConstants.hpp
++++ b/src/cpp/session/include/session/SessionConstants.hpp
+@@ -140,7 +140,7 @@
+ #ifdef QUARTO_ENABLED
+ # define kDefaultPandocPath        "bin/quarto/bin"
+ #else
+-# define kDefaultPandocPath        "bin/pandoc"
++# define kDefaultPandocPath        "@pandoc@"
+ #endif
+ 
+ #define kDefaultQuartoPath         "bin/quarto"

pkgs/applications/editors/rstudio/use-system-node.patch

@@ -21,7 +21,7 @@
 -      property="node.bin"
 -      value="/opt/rstudio-tools/dependencies/common/node/${node.version}/bin/node"
 -      file="/opt/rstudio-tools/dependencies/common/node/${node.version}/bin/node"/>
-+   <property name="node.bin" value="/usr/bin/node"/>
++   <property name="node.bin" value="@node@/bin/node"/>
 
     <property name="panmirror.dir" value="./panmirror/src/editor"/>
     <property name="panmirror.build.dir" value="./www/js/panmirror"/>