feat: support Mysql Upper Function

[raspberry-hu]

What this PR does:

Which issue(s) this PR fixes:

Fixes #513

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-commenter]

Codecov Report

Base: 36.26% // Head: 36.28% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (4debee6) compared to base (a586dd0).
Patch coverage: 78.57% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #515      +/-   ##
==========================================
+ Coverage   36.26%   36.28%   +0.02%     
==========================================
  Files         161      162       +1     
  Lines       21722    21736      +14     
==========================================
+ Hits         7877     7887      +10     
- Misses      12984    12987       +3     
- Partials      861      862       +1     

Impacted Files	Coverage Δ
pkg/runtime/function2/upper.go	78.57% <78.57%> (ø)
pkg/dataset/priority_queue.go	64.35% <0.00%> (-1.00%)	⬇️

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[jjeffcaii]

pls fix