chore: merge pull request aws#1462 from awslabs/release/v1.21.0

chore: merge pull request aws#1394 from awslabs/release/v1.20.1

Release/v1.20.1

Merge pull request aws#1382 from awslabs/release/v1.20.0

Release/v1.20.0

chore: merge pull request aws#1339 from awslabs/release/v1.19.1

chore: merge Release/v1.19.1 into master

chore: merge pull request aws#1291 from awslabs/release/v1.19.0

chore: merge release/v1.19.0 into master

feat: adding support for provisioned concurrency (aws#1284) (aws#1285)

chore: merge pull request aws#1280 from awslabs/release/v1.17.0

feat: support virtual sharding and stream failure processing (aws#1261)…

… (aws#1262)

chore: merge pull request aws#1201 from awslabs/release/v1.15.1

Release/v1.15.1

chore: merge pull request aws#1174 from awslabs/release/v1.15.0