Add resolutions to rsv

[rneher]

This PR adds different time resolutions to RSV builds, currently

• all-time
• 6y
• 3y

This is implemented by having one dense sample in the recent past, and adding 10% additional genomes before the cut-off. The latter is important for stability of the rooting and outlier filtering etc.

after merge, we need to adjust the manifest and the redirects.

[rneher]

Fixed the CI by updating the example data.

[rneher]

trial builds can be inspected at

https://nextstrain.org/staging/rsv/a/genome/3y
https://nextstrain.org/staging/rsv/a/genome/6y
https://nextstrain.org/staging/rsv/a/genome/all-time

https://nextstrain.org/staging/rsv/a/F/3y
https://nextstrain.org/staging/rsv/a/F/6y
https://nextstrain.org/staging/rsv/a/F/all-time

https://nextstrain.org/staging/rsv/a/G/3y
https://nextstrain.org/staging/rsv/a/G/6y
https://nextstrain.org/staging/rsv/a/G/all-time

https://nextstrain.org/staging/rsv/b/genome/3y
https://nextstrain.org/staging/rsv/b/genome/6y
https://nextstrain.org/staging/rsv/b/genome/all-time

https://nextstrain.org/staging/rsv/b/F/3y
https://nextstrain.org/staging/rsv/b/F/6y
https://nextstrain.org/staging/rsv/b/F/all-time

https://nextstrain.org/staging/rsv/b/G/3y
https://nextstrain.org/staging/rsv/b/G/6y
https://nextstrain.org/staging/rsv/b/G/all-time