fix(http): better handle unexpected `undefined` XSRF tokens (#47683)
fix(http): better handle unexpected `undefined` XSRF tokens (#47683)

`HttpXsrfTokenExtractor` allows returning `string|null` for an XSRF token,
and the interceptor checked if the returned token is `null`. However, some
implementations return `undefined` instead (behind an `any`) type, which
caused the interceptor to crash when trying to set an `undefined` value for
the header.

This commit makes the XSRF interceptor a little more resilient against such
broken implementations of the `HttpXsrfTokenExtractor` interface.

PR Close #47683

angular/angular,angular-indonesia/angular,angular/angular,gnomeontherun/angular,angular-indonesia/angular,angular-indonesia/angular,gnomeontherun/angular,gnomeontherun/angular,gnomeontherun/angular,angular/angular,angular/angular,angular-indonesia/angular