Add support for workingDirectory

[agentschmitt]

I would like to have support to set workingDirectory where the script runs and searches for the toolsDirectory.

Cause I have some trouble when running cake scripts that are not in root of the git repository.
I also use some tools manifest, but this cant be read by the action as its working directory seems to be root of git repository.

Error looks like this:
Run cake-build/cake-action@v1
dotnet tool restore
Es wurde keine Manifestdatei gefunden.

My repository looks like this:
scripts

• build1.cake
• build2.cake
• .config
  • dotnet-tools.json

When i run script without version "tool-manifest" it works, but i would like to stick the cake-version in manifest.
Also it creates 2 tools directories. one in root (with dotnet-cake.exe)
and one in scripts directory (with scripts dependencies) where my cake scripts are located.