Uploaders.S3: Replace unsafe characters in object key

See merge request !359

According to [the S3 docs][s3], the characters safe for use in object keys are:

* 0-9
* a-z
* A-Z
* !
* -
* _
* .
* *
* '
* (
* )

(The / character is not listed but mentioned being safe outside of the list.)

Several characters that are valid in filenames can cause problems, for example
spaces are not valid in URLs and need to be escaped,
sequences of spaces can become squeezed by S3,
some characters like \ are documented to require “significant special handling”.

To avoid these problems, this change encodes the filename
before using it as part of the S3 object name
by replacing all characters except those documented as “safe” with dashes.

[s3]: https://docs.aws.amazon.com/AmazonS3/latest/dev/UsingMetadata.html

update pleroma frontend

See merge request !357

html: add scrub policy tests

See merge request pleroma/pleroma!356

twitter api: add no_rich_text option to userview for account prefs

See merge request pleroma/pleroma!355

backend support for opting out of rich text on a per-account basis

See merge request pleroma/pleroma!354

user: implement dynamic refresh of profiles

See merge request pleroma/pleroma!350

Return 204 response on options request

See merge request pleroma/pleroma!347

Update mastodon frontend

Closes pleroma/mastofe#33

See: pleroma/pleroma!352

Update mastodon API to 2.5.0

Closes: pleroma/pleroma#298
Closes: pleroma/pleroma#299

See: pleroma/pleroma!351

Revert "Mastodon API: Fake support for loading filters"

See merge request pleroma/pleroma!348

This reverts commit c1d07da4.

The fake support was superseded by 6e030129 which actually implements the faked filters API.

This change removes the fake support and ensures that the actual implementation is used.

html: support mediaproxy for inline images

Closes #275

See merge request pleroma/pleroma!346