Replace SendTxRequest with FrontendTransaction

[sstanculeanu]

Reasoning behind the pull request

• SendTxRequest struct, used only on node api, can be replaced by FrontendTransaction for consistency

Proposed changes

• replace structures

Testing procedure

• standard system test with txs

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b209c7f) 80.34% compared to head (69ff36e) 80.26%.
Report is 1 commits behind head on rc/v1.7.0.

❗ Current head 69ff36e differs from pull request most recent head 16e5d20. Consider uploading reports for the commit 16e5d20 to get more accurate results

Additional details and impacted files

@@              Coverage Diff              @@
##           rc/v1.7.0    #5649      +/-   ##
=============================================
- Coverage      80.34%   80.26%   -0.08%     
=============================================
  Files            708      706       -2     
  Lines          94096    93908     -188     
=============================================
- Hits           75601    75378     -223     
- Misses         13187    13223      +36     
+ Partials        5308     5307       -1     

Files	Coverage Δ
api/groups/transactionGroup.go	98.31% <100.00%> (ø)

... and 40 files with indirect coverage changes

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[iulianpascalau]

👍
the transaction.FrontendTransaction's fields matches this one

[gabi-vuls]

Normal allin test: v1.5.13-dev-config-8c685c8e00 -> remove_sendtxrequest-16e5d20bd2

--- Specific errors ---

block hash does not match 1915
wrong nonce in block 647
miniblocks does not match 0
num miniblocks does not match 0
miniblock hash does not match 0
block bodies does not match 0
receipts hash missmatch 0

/------/

--- Statistics ---

Nr. of all ERRORS: 1
Nr. of all WARNS: 124
Nr. of new ERRORS: 1
Nr. of new WARNS: 1
Nr. of PANICS: 0

/------/

--- ERRORS ---

mx-testnet-gcp-mil-obs-0 :
Error: context deadline exceeded while closing the http server in gin/webServer 1

/------/

--- WARNINGS ---

mx-testnet-gcp-mil-node-29 :
Warn: trie recreate error: error = getNodeFromDB error: key not found for key root = 1

/------/