chore(benchmarks): memory allocation per function during page-load [s…

[vigneshshanmugam]

• part of Add benchmarks #26
• This PR uses the chrome allocation profiler to measure the memory allocation of top functions from the agent that might help identify memory leaks
• Generates a new build with keeping the function names of the apm agent to help with identify the functions with more memory allocation.

Adds some keys to the benchmark documents that matches with the function names that uses the most memory

   "memory.createResourceTimingSpan.bytes": 65664,
    "memory.generateRandomId.bytes": 33280,
    "memory.createResourceTimingSpans.bytes": 32864,
    "memory.getCurrentScript.bytes": 32816,
    "memory.patchFetch.bytes": 32816,
    "memory.baseExtend.bytes": 32784,
    "memory.isCORSSupported.bytes": 38376,

[codecov-io]

Codecov Report

Merging #508 into master will increase coverage by 0.47%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #508      +/-   ##
==========================================
+ Coverage   93.87%   94.34%   +0.47%     
==========================================
  Files          42       43       +1     
  Lines        1991     2245     +254     
  Branches      395      489      +94     
==========================================
+ Hits         1869     2118     +249     
- Misses        119      124       +5     
  Partials        3        3

Impacted Files	Coverage Δ
packages/rum/src/apm-base.js	94.01% <0%> (-2.57%)	⬇️
packages/rum-core/src/common/patching/xhr-patch.js	90.78% <0%> (-0.35%)	⬇️
packages/rum-core/src/opentracing/tracer.js	91.83% <0%> (-0.17%)	⬇️
...s/rum-core/src/performance-monitoring/breakdown.js	95.65% <0%> (-0.13%)	⬇️
packages/rum-core/src/common/apm-server.js	81.29% <0%> (-0.12%)	⬇️
...ckages/rum-core/src/performance-monitoring/span.js	100% <0%> (ø)	⬆️
packages/rum-core/src/common/url.js	100% <0%> (ø)	⬆️
packages/rum-core/src/common/truncate.js	100% <0%> (ø)	⬆️
...e/src/performance-monitoring/capture-navigation.js	100% <0%> (ø)	⬆️
packages/rum-core/src/common/context.js	100% <0%> (ø)
... and 5 more

[hmdhk]

Thanks @vigneshshanmugam.
A general note, I think we should separate our build scripts for the final dist and the debugging and testing. Currently, it's hard to tell which function is used for what.