Modified refreshOn in MSAL Common Silent Flow to return cached token before refreshing in the background

[Robbie-Microsoft]

refreshOn functionality already exists in Silent Flow. That is, if a token needs to be refreshed but is not expired, an error was thrown and the token was refreshed. This PR contains changes that will now return the cached token if it needs to be refreshed and is not expired, while also refreshing the token in the background.

[codecov-commenter]

Codecov Report

Merging #6397 (5e38ebe) into dev (81d34b4) will decrease coverage by 1.78%.
Report is 312 commits behind head on dev.
The diff coverage is 61.03%.

Flag	Coverage Δ
msal-angular	96.73% <ø> (+0.22%)	⬆️
msal-browser	85.32% <ø> (-1.15%)	⬇️
msal-common	83.50% <ø> (-1.05%)	⬇️
msal-core	?
msal-node	80.16% <ø> (-3.23%)	⬇️
msal-node-extensions	68.51% <60.77%> (-7.13%)	⬇️
msal-react	94.24% <ø> (-0.45%)	⬇️
node-token-validation	?

Files Changed	Coverage Δ
...ions/msal-node-extensions/src/utils/Environment.ts	20.51% <0.00%> (-22.08%)	⬇️
lib/msal-angular/src/constants.ts	100.00% <ø> (ø)
lib/msal-angular/src/msal.broadcast.service.ts	100.00% <ø> (ø)
lib/msal-angular/src/msal.guard.ts	90.78% <ø> (+0.64%)	⬆️
lib/msal-angular/src/msal.interceptor.ts	100.00% <ø> (ø)
lib/msal-angular/src/msal.module.ts	100.00% <ø> (ø)
lib/msal-angular/src/msal.navigation.client.ts	93.33% <ø> (+0.47%)	⬆️
lib/msal-angular/src/msal.redirect.component.ts	100.00% <ø> (ø)
lib/msal-angular/src/msal.service.ts	100.00% <ø> (ø)
lib/msal-angular/src/packageMetadata.ts	100.00% <ø> (ø)
... and 69 more

... and 164 files with indirect coverage changes

[bgavrilMS]

No sleep in tests; Errors must be actionable.