Reworks file status parsing -- uses consistent regex now

Adds `${committerAgo}`, `${committerAgoOrDate}`, `${committerDate}`
Repurposes `${authorAgo}` & replaces current ones w/ `${author}, ${ago}`
Repurposes `${authorAgoOrDate}` & replaces w/ `${author}, ${agoOrDate}`
Renames defaultDateType to defaultDateSource
Points format settings to new formatting wiki

Fixes #537

Reworks branch parsing to use for-each-ref

Disables commands for the deleted or missing sha
Adds getNextDiffUris & getNextUri
Renames getDiffWithPreviousForFile to getPreviousDiffUris
Renames getPreviousRevisionUri to getPreviousUri

Reworks file status parsing -- uses consistent regex now

Adds getDiffWithPreviousForFile & getPreviousRevisionUri

Adds originalPath token

Adds hovers.changesDiff setting for line vs hunk diff

Avoids bogus merge commits in file history when following renames

Removes "Branch or Tag" from all commands
Changes openFileRevisionFrom allow entering references
Fixes missing views.compare.selectForCompare from command palette

Splits App into AppBase & AppWithConfigBase for impl of new webviews