When installing a .NET local tool, create the tool manifest if one does not exist

When a user tries to install a .NET tool as a local tool on a folder that does not contain the manifest, we get an error Cannot find a manifest file.

> dotnet tool install --local Cake.Tool --version 0.38.4

Cannot find a manifest file.
For a list of locations searched, specify the "-d" option before the tool name.
If you intended to install a global tool, add `--global` to the command.
If you would like to create a manifest, use `dotnet new tool-manifest`, usually in the repo root directory.

However, if the user tries to update an existing local tool, dotnet tool is able to update the existing manifest:

dotnet new tool-manifest
dotnet tool install --local Cake.Tool --version 0.38.4
dotnet tool update --local Cake.Tool

Tool 'cake.tool' was successfully updated from version '0.38.4' to version '0.38.5' (manifest file /Users/augustoproiete/.config/dotnet-tools.json).

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TL;DR; It would be great if dotnet tool install automatically created the tool manifest, if one does not exist when installing a local tool, instead of failing with an error.

[timheuer]

Finding an analog, NPM does this by default as well with package.json and puts it in the right place. Users who do npm install moment for example, get a non-global package and a package.json dropped in the right place. We should have the similar and easy experience reducing the ceremony for such things.

[augustoproiete]

The side of doing that is we could potentially generating manifest file accidentally on unexpected locations. And people could run unexpected tool.

Add a --force or --trust-me parameter so users can convince dotnet tool that they know what they are doing? 😄