[Meta] Added a search link to the community sidebar

I added a search option to a community's sidebar - this will be helpful to find past answers but also to check and see if someone has already asked that question recently.

For example, here are the latest posts on password managers: https://lemmy.ml/search?q=password&type=Posts&listingType=All&communityId=8&page=1&sort=TopAll

I've set it to search through Lemmy.ml - this has the pro that it will be able to find all content because it's a local community. It has the con that most people won't be able to interact directly with the content as they are not subscribed via their own instance.

I was hoping to use a relative search URL and search through the user's instance. This won't work as each instance numbers the communities differently: the communityId on Lemmy.ml is different than on my own instance.

Is this helpful for anyone? Do you have any suggestions on how to improve it further?