feat: empty body default to empty object

[ghost]

When sending no request body with express, it is sending an empty object by default {}. But when using fastify, for example, the body is undefined.

Since DaVinci is expecting body to be an object, validation is failing with undefined.

With this fix, we make sure if there is to be a body, is always an empty object.

This arises from a PUT request that we have in one of our repos where we are not sending a body, just so that the entity is marked as updated with the right timestamp.

[codecov]

Codecov Report

Merging #263 (53b168c) into master (57cadb5) will not change coverage.
Report is 1 commits behind head on master.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #263   +/-   ##
=======================================
  Coverage   74.86%   74.86%           
=======================================
  Files          27       27           
  Lines         915      915           
  Branches      271      272    +1     
=======================================
  Hits          685      685           
  Misses        105      105           
  Partials      125      125           

Flag	Coverage Δ
core	87.04% <ø> (ø)
http-server	78.69% <100.00%> (ø)
http-server-express	55.68% <ø> (ø)
reflector	80.64% <ø> (ø)

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Files Changed	Coverage Δ
packages/http-server/src/HttpServerModule.ts	78.52% <100.00%> (ø)