refactor: Improved const-correctness for TrackContainer in Examples

[paulgessinger]

Also includes a fix of a missing method in the ConstVectorTrackContainer class.

[codecov]

Codecov Report

Merging #1871 (9ae2c87) into main (910ec13) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1871   +/-   ##
=======================================
  Coverage   49.50%   49.50%           
=======================================
  Files         407      407           
  Lines       22646    22646           
  Branches    10334    10334           
=======================================
  Hits        11210    11210           
  Misses       4247     4247           
  Partials     7189     7189           

Impacted Files	Coverage Δ
...re/include/Acts/EventData/VectorTrackContainer.hpp	64.70% <ø> (ø)

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[github-actions]

📊 Physics performance monitoring for 9ae2c87

Full report
Seeding: seeded, truth estimated, orthogonal
CKF: seeded, truth smeared, truth estimated, orthogonal
IVF: seeded, truth smeared, truth estimated, orthogonal
Ambiguity resolution: seeded, orthogonal
Truth tracking
Truth tracking (GSF)

Vertexing

Vertexing vs. mu

IVF seeded

IVF truth_smeared

IVF truth_estimated

IVF orthogonal

Seeding

Seeding seeded

Seeding truth_estimated

Seeding orthogonal

CKF

CKF seeded

CKF truth_smeared

CKF truth_estimated

CKF orthogonal

Ambiguity resolution

seeded

Truth tracking (Kalman Filter)

Truth tracking

Truth tracking (GSF)

Truth tracking

[andiwand]

looks good - just left one unrelated question