DIP17/DalamudPackager: update to generate JSON + archives from csproj

[philpax]

This issue assumes https://github.com/goatcorp/DIPs/pull/38 is merged.

All plugin developers will be required to make DalamudPackager the final step of their build process, and to move their existing pluginname.json metadata into the project, like so:

<ProjectExtensions>
    <DalamudPlugin>
        <ApiLevel>6</ApiLevel>
        <Author>Ottermandias</Author>
        <Name>GatherBuddy</Name>
        <Punchline>Simplify Gathering and Fishing.</Punchline>
        <Description>Adds commands to simplify gathering by finding nodes and fish and their locations via item name and a UI to keep track of special uptime and weather conditions.</Description>
        <IconUrl>https://raw.githubusercontent.com/Ottermandias/GatherBuddy/main/images/icon.png</IconUrl>
        <Tags>
            <Tag>Gathering</Tag>
            <Tag>Fishing</Tag>
            <Tag>Miner</Tag>
            <Tag>Botanist</Tag>
            <Tag>Weather</Tag>
            <Tag>Alarms</Tag>
            <Tag>Timer</Tag>
        </Tags>
        <Hidden>False</Hidden>
    </DalamudPlugin>
</ProjectExtensions>

DalamudPackager will then read these properties, as well as additional properties from the csproj and other sources, and produce a plugin.json which it then combines with the plugin itself to produce a $pluginname.zip.

This $pluginname.zip can then be consumed by both Dalamud (see #868) and published to the DalamudPlugins repo. It contains everything required to load the plugin, which should simplify both development and deployment.

DalamudPackager already produces a zip; the primary changes will be to make the zip the primary mode of output, and for the packager itself to generate the JSON, instead of the developer.