feat(tm2): Add missing unit tests for tm2/pkg/crypto/client

[linhpn99]

Blocked by #2309

From @moul 's request to add unit tests, I realized there are many code sections (maketx, call, query, etc.) that are not covered by unit tests. Obviously, this PR is created to address all of them :)

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

Attention: Patch coverage is 78.57143% with 6 lines in your changes missing coverage. Please review.

Project coverage is 55.17%. Comparing base (95115c0) to head (d1a7e29).
Report is 60 commits behind head on master.

Files	Patch %	Lines
tm2/pkg/crypto/keys/client/broadcast.go	55.55%	2 Missing and 2 partials ⚠️
tm2/pkg/crypto/keys/client/send.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2350      +/-   ##
==========================================
+ Coverage   55.02%   55.17%   +0.15%     
==========================================
  Files         595      595              
  Lines       79662    79669       +7     
==========================================
+ Hits        43832    43960     +128     
+ Misses      32514    32384     -130     
- Partials     3316     3325       +9     

Flag	Coverage Δ
contribs/gnodev	25.65% <ø> (-0.35%)	⬇️
contribs/gnofaucet	14.46% <ø> (ø)
contribs/gnokeykc	0.00% <ø> (ø)
contribs/gnomd	0.00% <ø> (ø)

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