Workspaces via sourcecache MR 2

closes #1140 (closed) and adds a test for soft reset of workspaces

• benchmark (after feedback)

conflicts with !1637 (closed)

====show====
master_results time: 6.5
traveltissues_1140-softreset_results time: 6.52
which is a +0.31% difference
master_results memory: 171.0
traveltissues_1140-softreset_results memory: 171.0
which is a -0.0% difference
====build-4====
master_results time: 691.85
traveltissues_1140-softreset_results time: 698.15
which is a +0.91% difference
master_results memory: 197.0
traveltissues_1140-softreset_results memory: 197.0
which is a -0.0% difference
====build-8====
master_results time: 695.46
traveltissues_1140-softreset_results time: 699.73
which is a +0.61% difference
master_results memory: 197.0
traveltissues_1140-softreset_results memory: 197.0
which is a -0.0% difference
====build-12====
master_results time: 812.24
traveltissues_1140-softreset_results time: 684.8
which is a -15.69% difference
master_results memory: 195.0
traveltissues_1140-softreset_results memory: 197.0
which is a +1.03% difference
====show cached====
master_results time: 13.97
traveltissues_1140-softreset_results time: 13.99
which is a +0.14% difference
master_results memory: 199.0
traveltissues_1140-softreset_results memory: 199.0
which is a -0.0% difference