Add fantomas configuration file

Source will be formatted using this command:
fantomas --config fantomas-config.json --recurse src/GWallet.Backend/

This version of fantomas doesn't crash anymore when formatting it:
dotnet tool install -g fantomas-tool --add-source https://www.myget.org/F/fantomas/api/v3/index.json --framework netcoreapp3.1 --version 4.0.0-alpha-008-alpha-190

Last issues left to fix (by order of priority, top is more important):

- fsprojects/fantomas#898 (comment)

- fsprojects/fantomas#907

- fsprojects/fantomas#905

- fsprojects/fantomas#908

- fsprojects/fantomas#712

- fsprojects/fantomas#904

fantomas-config.json

@@ -0,0 +1,24 @@
+{
+  "IndentSpaceNum":4,
+  "PageWidth":80,
+  "SemicolonAtEndOfLine":false,
+  "SpaceBeforeParameter":true,
+  "SpaceBeforeLowercaseInvocation":true,
+  "SpaceBeforeUppercaseInvocation":true,
+  "SpaceBeforeClassConstructor":true,
+  "SpaceBeforeMember":true,
+  "SpaceBeforeColon":false,
+  "SpaceAfterComma":true,
+  "SpaceBeforeSemicolon":false,
+  "SpaceAfterSemicolon":true,
+  "IndentOnTryWith":true,
+  "SpaceAroundDelimiter":true,
+  "MaxIfThenElseShortWidth":0,
+  "MaxRecordWidth":0,
+  "MaxFunctionBindingWidth":0,
+  "MaxValueBindingWidth":80,
+  "MultilineBlockBracketsOnSameColumn":true,
+  "NewlineBetweenTypeDefinitionAndMembers":true,
+  "KeepIfThenInSameLine":true,
+  "StrictMode":false
+}