Improve the visibility of non-Flathub Flatpak & non-Flatpak installation methods for clients

Currently, even though some clients (e.g., [Commet](https://github.com/matrix-org/matrix.org/blob/main/content/ecosystem/clients/commet.md?plain=1#L25)) have metadata related to non-Flathub Flatpak and non-Flatpak installation methods, we don't display this information. This can, and has [led](https://matrix.to/#/!L58ME6ufiP49v97UIOBIpvWKEgj4912JmECPuDzlvCI/$ZEvmkHQMXnMpw02rcIOKvmI2R6A91fN3HrcMTb_z-kw?via=matrix.org&via=mozilla.org&via=unredacted.org), to people thinking that a client isn't available on their platform. I think we should improve on this matter.

Start with content/ecosystem/clients/commet.md and inspect how its installation metadata is rendered on the matrix.org client pages. Confirm the existing non-Flathub Flatpak and non-Flatpak fields, then make both methods visible and verify that the client page shows them clearly.

Written by the indexing model from the issue text.