Changes working tree/branch comparision selection to be per-comparison

The PR adds dedicated `GitLens` aka.ms link to the Live Share badge in `readme.md`.

Replaces "recent incoming changes" node

Causes too much confusion vs -G which better matches user expectations

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

Adds hovers.changesDiff setting for line vs hunk diff

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

Adds author email to commit node tooltips
Adds ${email} token to many formats

Tweaks shorten logic to only allow >=5 chars & always append any suffix

Limits stage/unstage to working tree folders
Adds stage/unstage to the folder's inline toolbar
Adds recognition for Tony Brix's contribution

Changes fetch date to  respect date settings

Updates BACKERS