T-compiler meeting agenda: add Zulip discussion links to MCPs and FCPs

[apiraino]

MCPs and FCPs all have a corresponding Zulip chat link for discussion before being approved (or declined).

In order to facilitate reaching this discussion happening on Zulip, this patch retrieves the first comment of an MCP/FCP, parses the corresponding Zulip link and add it to the T-compiler agenda.

Example of how the list of MCP/FCP look before this patch:

• Old MCPs (not seconded, take a look)
  • "Consistently use "region" terminology in later stages of the compiler" compiler-team#634 (last review activity: 3 months ago)

Example of how the list of MCP/FCP look after this patch:

• Old MCPs (not seconded, take a look)
  • "Consistently use "region" terminology in later stages of the compiler" compiler-team#634 (Zulip) (last review activity: 3 months ago)

This idea was mentioned in a T-compiler meeting (on Zulip, of course).

Thanks for looking at this patch!

r? @spastorino