fix(cli): enforce num keys greater than or equal to num builders

[dancoombs]

Proposed Changes

• On startup check that the configured number of keys is greater than or equal to the total number of builders across the two entrypoints.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 15 lines in your changes are missing coverage. Please review.

Project coverage is 55.15%. Comparing base (f2f3dd8) to head (72781f0).

Additional details and impacted files

Files	Coverage Δ
bin/rundler/src/cli/builder.rs	0.00% <0.00%> (ø)

Flag	Coverage Δ
unit-tests	55.15% <0.00%> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
rundler binary	0.00% <0.00%> (ø)
builder	50.60% <ø> (ø)
dev	0.00% <ø> (ø)
pool	64.87% <ø> (ø)
provider	14.77% <ø> (ø)
rpc	25.46% <ø> (ø)
sim	77.53% <ø> (ø)
tasks	∅ <ø> (∅)
types	65.88% <ø> (ø)
utils	18.28% <ø> (ø)

[0xfourzerofour]

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