use rlib example actions

[KrishanBhasin]

Description

Move from TravisCI to GitHub Actions for our CI pipeline.

Motivation and Context

Travis CI have undergone some changes and with the utility of GitHub Actions no longer seems like the right fit for the CI for this package.
This PR moves us over to GitHub actions, using the templates from https://github.com/r-lib/actions

How Has This Been Tested?

I have been running the CI against my personal fork at https://github.com/KrishanBhasin/dataCompareR/

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[KrishanBhasin]

pkgdown failing due to r-lib/pkgdown#1378

will add the keywords

[KrishanBhasin]

Still getting warnings:

Warning messages:
1: Topics missing from index: 
* allVarMatchMessage
* checkEmpty
* checkForRCompareCol
* checkKeysExist
* checkNA
* checkUniqueness
* cleanColNames
* coerceData
* coerceFactorsToChar
* collapseClasses
* colsWithUnequalValues
* compareData
* compareNames
* createAntiSubset
* createCleaningInfo
* createColMatching
* createCompareObject
* createMeta
* createMismatchObject
* createMismatches
* createReportText
* createRowMatching
* createTextSummary
* currentObjVersion
* executeCoercions
* getCoercions
* getMismatchColNames
* is.dataCompareRobject
* isNotNull
* isSingleNA
* listObsNotVerbose
* listObsVerbose
* locateMismatches
* makeValidKeys
* makeValidNames
* matchColumns
* matchMultiIndex
* matchNoIndex
* matchRows
* matchSingleIndex
* metaDataInfo
* mismatchHighStop
* orderColumns
* outputSectionHeader
* prepareData
* processFlow
* rcompObjItemLength
* rounddf
* subsetDataColumns
* trimCharVars
* updateCompareObject
* updateCompareObject.cleaninginfo
* updateCompareObject.colmatching
* up [... truncated] 
2: Failed to parse example for topic 'makeValidKeys' 

[KrishanBhasin]

It would be nice to have the pkgdown site built (but not published) on PRs, and built & published on commits to master

[KrishanBhasin]

We could do this using conditionals

An example from those docs:

name: CI
on: push
jobs:
  prod-check:
    if: ${{ github.ref == 'refs/heads/main' }}
    runs-on: ubuntu-latest
    steps:
      - run: echo "Deploying to production server on branch $GITHUB_REF"