feat: replace opentracing with opentelemetry

[GeorgeMac]

Closes #576

This is an attempt to replace the open-tracing libraries with the open-telemetry alternatives.

The PR does not attempt to change any of the current Flipt configuration for tracing.
Instead, it demonstrates how we can move to the otel abstractions for tracing, without touching existing configuration.

I propose we explore furthering the configurations options in a subsequent PR.
(e.g. support for more exporters and so on).

The most significant change is the slight deviation in the span and trace contents for SQL.
Though, there are some subtle differences in the gRPC ones as well.
See the following images for an illustration:

OpenTracing:

OpenTelemetry:

• No leading slash on the operation names.
• No longer producing args as tags.
  I would argue this is preferable. There is no need to index all these traces by the arguments presented to each query.
  Might be favourable down the line to introduce SQL arguments as span log statements.
• Uses . over - as delimiter when producing span names.
• query tag becomes db.statement.

To get SQL support, I have added the https://github.com/XSAM/otelsql library.
As this was advised in an otel related issue as the best supported implementation for now.

Take it or leave it: I added a Multistage build alternative Dockerfile.
This was just useful for debugging with docker compose.
Since I could get an equivalent alpine image built with it a little easier.

[codecov-commenter]

Codecov Report

Merging #1053 (6675cd6) into main (f4a1f50) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1053      +/-   ##
==========================================
+ Coverage   81.33%   81.40%   +0.06%     
==========================================
  Files          17       17              
  Lines        1822     1828       +6     
==========================================
+ Hits         1482     1488       +6     
  Misses        265      265              
  Partials       75       75              

Impacted Files	Coverage Δ
storage/sql/db.go	94.64% <100.00%> (+0.30%)	⬆️

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[markphelps]

🎉 amazing! ty checking this out now!

[markphelps]

thanks again @GeorgeMac !!!