Split a few easy plugins in a Ltac1-free core and a Ltac1 syntax plugin

[ppedrot]

We do that for plugins that do not require heavy infrastructural changes, namely:

• cc
• firstorder
• nsatz

This is needed for #19032.

Overlays:

• Adapt w.r.t. coq/coq#19313. mattam82/Coq-Equations#611
• Adapt w.r.t. coq/coq#19313. ejgallego/coq-lsp#802
• Adapt w.r.t. coq/coq#19313. coq-tactician/coq-tactician#86

[SkySkimmer]

if you want to keep the _core plugins in the same directory you need to handle them in findlib_plugin_fixup in coq_rules.ml

I think that's why windows is failing

[coqbot-app]

🔴 CI failure at commit 87b6354 without any failure in the test-suite

✔️ Corresponding job for the base commit 16e3f49 succeeded

❔ Ask me to try to extract a minimal test case that can be added to the test-suite

🏃 @coqbot ci minimize will minimize the following target: ci-tactician

• You can also pass me a specific list of targets to minimize as arguments.

[ppedrot]

The coq_lsp dev is missing some pieces of overlay but I'm not quite sure about how to fix the errors.

[SkySkimmer]

@coqbot merge now

[coqbot-app]

@SkySkimmer: Please take care of the following overlays:

• 19313-ppedrot-ltac1-split-some-plugins.sh