licenses: convert license tags to SPDX

lib: change @{file} antiquote to @{path}

When extracting files for C parser and AutoCorres standalone releases,
we don't want Isabelle to fail a build when files referred to in
`@{file}` antiquotations no longer exist. Using `@{path}` avoids this
problem.

global: isabelle update_cartouches

lib: add method to shorthand larger methods

Adds the `supply_local_method` command and `local_method` methods,
which store and apply methods as a way to shorten repeated
references to large or complicated methods.