Define EFTLagrangianExclDeriv for the Higgs field

[nateabr]

The goal of this draft is to construct HiggsBoson.EFTLagrangianExclDeriv in a way that is compatible with the direction of #1415.

We are beginning with the generic symmetric-algebra foundations needed to describe Higgs monomials and define coefficient projections.

The next step is to define the Higgs field specification and generator-module basis, then form EFTLagrangianExclDeriv as its symmetric algebra.

[github-actions]

Thank you for this PR, which will now be reviewed. If submitting to ./Physlib or ./QuantumInfo, please see our review guidelines if you are not familiar with the process. You should expect a back and forth with a reviewer before your PR is merged. See also that link for how to add appropriate labels to your PR. The PR will also go through a number of automated checks. You can learn more about these here, including how to run them locally.

If you are submitting to ./PhyslibAlpha there will be a lighter review process, though your PR must still pass the automated checks.

If you want to bring attention to this PR, please write a message on this thread of the Lean Zulip.

Important: If a reviewer adds an awaiting-author label to your PR, once you have addressed the review comments, please remove that label by adding a comment with -awaiting-author. This helps us keep track of reviews.