Apply highlighting to more builtin forms by default

[kisaragi-hiu]

Existing logic already works well enough. It is enough to just add these forms to the default values.

• let forms like if/when-let and letrec
• builtin define-inline also has the same syntax as defun
• try to highlight pcase-lambda and pcase-dolist like has already been done for pcase-let
• highlight variants of condition-case

While not all features of all forms* here are highlighted, this is already more useful than not applying the highlighting to them.

*: like when-let and if-let's variable omitting