Changelog: Add 1.0 changes

[jku]

Leaving as draft for now:

• I believe I've listed all relevant changes so far (some trivial PRs are not listed) but obviously there are likely to be a few more changes before 1.0
• The text section could be improved, but I'll do that with a fresher brain

[coveralls]

Pull Request Test Coverage Report for Build 1863174413

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 98.574%

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Totals
Change from base Build 1852769022:	0.2%
Covered Lines:	1095
Relevant Lines:	1107

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💛 - Coveralls

[ivanayov]

Seems like almost everything is present. Leaving some minor comments.

Should we add bug fixes?

• Metadata API: Role keyids is not ordered #1478 /role keyids still not ordered #1752
• ngclient: should clean temp file if write fails #1575
• Not sure if this was present before 0.20.0: ngclient: throws securesystemslib errors #1761

[jku]

Should we add bug fixes?

They should be in the list, just with the PR number and not the issue number (I can see an argument for using issue numbers: it's just potentially a lot more work since git log --merges v0.20.0..origin/develop gives a good initial list of PRs, but a complete list of issues is much harder to collect).

Out of your list all others have PRs in the list except 1754 and 1478: the latter was "fixed" last summer already but the former does seem to have the wrong issue number in the changelog. Thanks!

I fixed that and rebased to include the latest PRs 1850, 1848, 1855, 1809.

[ivanayov]

It looks good this way as well (i.e. without specific "Bug fixes" section).

I think that after having all latest required PRs merged (including the not yet opened for #1852) this should be good to go.

[jku]

rebased, added a commit that documents the new PRs in that rebase (this can be squashed, just trying to make this easier to review)

[ivanayov]

Looks good to me.

[jku]

rebased again, added a commit that documents the new merges in that rebase (this can be squashed, just trying to make this easier to review)

[MVrachev]

I had a look at all commits after release 0.20.0 and it seems that all changes are here.
LGTM!

[lukpueh]

Superseded by #1873