meson: Install all systemd units

[leiyu-bytedance]

Previously the systemd units were not installed and it depends on the bitbake recipe (in meta-openembedded) to install the service only.

Update the meson.build and install all the units. The bitbake recipe will need to be updated to add missing units to SYSTEMD_SERVICE:${PN}.

[jk-ozlabs]

So these units were a bit of a draft in their current state, and don't (yet!) mean to be a fully-formed system MCTP config.

Does this mean they're working for your environment? Any changes in the infrastructure around these that you would propose?

[leiyu-bytedance]

Yes, to integrate the recipe into BMC and make it useful, we need all the units to be installed.
So in the bitbake recipe, additional changes are needed as well:

SYSTEMD_SERVICE:${PN}:append = " \
    mctp.target \
    mctp-local.target \
"

[jk-ozlabs]

OK, been thinking about this one a bit. The installation of targets & config data is really a distro-specific thing; we can't really assume that the systemd units have the correct dependencies, are properly integrated with other units, or even that systemd is available.

Given that installation should be managed by the distro, I'd prefer that we don't install them in the meson targets.

I'll close for now, but am happy to continue discussion if you have counterpoints. Feel free to re-open.