Version EC separately

[crawfxrd]

I want to start moving towards providing updates for individual components (SBIOS, EC, CSME) separately (system76/firmware#534). As part of this, we need to version the EC separately from the SBIOS.

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The original rationale for having the EC version match the SBIOS version was to ensure that compatible versions of each were installed. So we set the EC version to the SBIOS version and always flash both of them, even if only one actually changed.

In the future, this would replaced by some mechanism that checks for a minimum supported/compatible version. My explanation from the linked issue:

Add a comparable mechanism to LVFS MetaInfo's "requires" field, indicating relations between firmware components. e.g.: Some BIOS version 1.07.06 requires at least EC version 1.07.02. This also means that we need to be able to sort releases (currently sorted from newest to oldest in changelog.json by virtue of JSON arrays preserving element order).