Cleanup: use absl::nullopt in components/

@sdefresne spotted many places in components/ where absl::nullopt could
be used.

I was helped by the following script. Then I did some manual changes.

Script:
```
cd components

git grep " absl::optional<[^() ]*>()" \
     | cut -f1 -d: \
     | grep \
       -e "\.h" \
       -e "\.cc" \
       -e "\.mm" \
     | sort \
     | uniq \
     | xargs sed -i "s/\([^:?]\) absl::optional<[^() ]*>()/\1 absl::nullopt/g"

cd ..
git cl format
```

Bug: chromium:1500249
Change-Id: I5613b2f25b8855d7de8ee267e90c075861db9a86
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5238088
Auto-Submit: Arthur Sonzogni <arthursonzogni@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1274850}