chore: rename modal-named arguments/variables related to SendConfirmation

[sviderock]

Description

This PR is related to some renames caused by removal of a modal version of SendConfirmation screeen. The following changes are applied:

• rename Screens.SendConfirmationModal to Screens.SendConfirmationFromExternal
• rename fromModal to fromExternal arguments/variables in files related to the Send flow

Test plan

No extra tests needed, all the existing tests work as intended

Related issues

Relates to RET-1295

Backwards compatibility

Yes

Network scalability

If a new NetworkId and/or Network are added in the future, the changes in this PR will:

• Continue to work without code changes, OR trigger a compilation error (guaranteeing we find it when a new network is added)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.10%. Comparing base (dcac9cf) to head (b7a7e6a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6454      +/-   ##
==========================================
- Coverage   89.11%   89.10%   -0.01%     
==========================================
  Files         731      731              
  Lines       31859    31859              
  Branches     5764     5764              
==========================================
- Hits        28390    28389       -1     
- Misses       3423     3424       +1     
  Partials       46       46              

Files with missing lines	Coverage Δ
src/fiatExchanges/saga.ts	85.86% <100.00%> (ø)
src/navigator/Screens.tsx	100.00% <100.00%> (ø)
src/send/SendConfirmation.tsx	94.44% <100.00%> (ø)
src/send/actions.ts	100.00% <ø> (ø)
src/send/saga.ts	77.01% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[sviderock]

Considering that this is only used for Bidali and the redirect is gonna come from the "external" source (dapp in this case) - I figured this name might fit well.

[jeanregisser]

🚀