Add updatecli subcommand to generate json schema

[olblak]

Add updatecli subcommand to generate json schema

• Require SCM/Source ID case insensitivity #444

PR related to #540 but the current one focus on generating json schema while #540 test updatecli manifest with json schema

Fix #524

The current pullrequest introduces several requirements

1. To retrieve field description, a comment must be one line maximum and me precede the field such

// Source defines parameters to retrieve an information from a specific location
type Source struct {
    // Title defines a source title
    title string // This is not a valid comment anymore
} 

2. Configuration key must be lowercase to be valid, while we could use another convention, we can't mix them.

--- 
    sources:
        default: 
            scmID: # not valid
            scmid: # valid  

Test

To test this pullrequest, you can:

1. Ensure that test in package github.com/pkg/core/jsonschema are passing.

make test

2. You can try to generate an Updatecli jsonschema using the new jsonschema argument

go build -o bin/updatecli && ./bin/updatecli jsonschema --directory schema

3. Finally, you can configure your IDE such as vscode to match files like ["/updatecli.di//.yaml","/updatecli.di//.yml","/updatecli.di//*.tpl"] with the jsonschema file that you generated locally such as "$HOME/Projects/Updatecli/updatecli/schema/config.json" as explained on vscode documentation

Additional Information

Tradeoff

/

Potential improvement

This pullrequest won't be usable as is as we need additional cleanup.
.1 Ensure that every field expected lowercase value. for example this tag must be removed

[dduportal]

👏

[lemeurherve]

Hardcoded warning sign